Php faiz hesaplama

<script>
                        


                        function krediHesapla(pesinat,tutar,ay){

                        number_format = function (number, decimals, dec_point, thousands_sep) {
                        number = Number(number).toFixed(decimals);

                        var nstr = number.toString();
                        nstr += '';
                        x = nstr.split('.');
                        x1 = x[0];
                        x2 = x.length > 1 ? dec_point + x[1] : '';
                        var rgx = /(\d+)(\d{3})/;

                        while (rgx.test(x1))
                        x1 = x1.replace(rgx, '$1' + thousands_sep + '$2');

                        return x1 + x2;
                        }

                        let kredi = Math.round(tutar);  
                
                        
                        let vade = ay;
                        let faiz = 2.1;
                        let bsmv = 0.05;
                        let kkdf = 0.15;
                        let vergi_faiz = (faiz / 100) * (1 + bsmv + kkdf);
                        let deger1 = vergi_faiz * Math.pow((1+vergi_faiz),vade);
                        let deger2 = Math.pow((1+vergi_faiz),vade) - 1;
                        let taksit = kredi * deger1/deger2;
                        let toplamodeme = taksit*vade;
                        let pesinatne = Math.round(pesinat);  
                      

                        let toplamodemepesinatdahil = Number(toplamodeme)+Number(pesinatne);
                        $('#aylik_tutar').html(number_format(taksit, 0, ',', '.')+" TL");
                        $('#taksit_sayisi').html(vade+" Ay");
                        $('#aylik_odeme_tutar').html(number_format(taksit, 0, ',', '.')+" TL");
                        $('#toplam_borc_tutari').html(number_format(toplamodeme, 0, ',', '.')+" TL");
                        $('#toplam_odeme').html(number_format(toplamodemepesinatdahil, 0, ',', '.')+" TL");
                        $('#vadeform').val(vade);
                        
                        }
                        </script>
                    
                        <div class="sidebar-widget widget-vendor mb-30 bg-grey-9 box-shadow-none fiyatBar">
                            <div class="priceTitle">
                                <h3>Peşin Satış Fiyatı: <span style="color: #22232a; font-size: 1rem;"><?php echo fiyat($id); ?></span>
                                </h3>
                            </div>
                            <div class="priceinfo">

                                <div class="priceinfofinal">
                                    <strong
                                        style="display: inline-block; font-size: 40px; font-weight: 900;color:#fd562a"
                                        id="aylik_tutar"></strong>
                                    <span style="display: inline-block;"> Taksitle</span>
                                </div>

                            
                            </div>

                            <div class="installment-card">
                                <div class="card-title text-center mb-2">
                                    <h5>TAKSİT HESAPLA</h5>
                                </div>
                                <div class="calculator" id="showcase_calculator">
                                    <div class="row gutter-7" style="margin-bottom: 0;height: auto;">
                                    <div class="col">
                                    <div class="payment-input">
                                        <label>Peşinat Seç</label>
                                        <div class="yuzde-select-div" id="pesinat-select-div"
                                            style="display: table-cell;">
                                            <form id="pesinat-hesapla">
                <label><input type="radio" class="option-input radio" name="pesinat-orani" checked="" onchange="pesinatOraniGuncelle('30')" value="30">%30</label>
                <label><input type="radio" class="option-input radio" name="pesinat-orani" checked="" onchange="pesinatOraniGuncelle('40')" value="40">%40</label>
                <label><input type="radio" class="option-input radio" name="pesinat-orani" checked="" onchange="pesinatOraniGuncelle('50')" value="50">%50</label>
                                            </form>
                                        </div>
                                    </div>
                                </div>
                                <div class="col" style="max-width:40%;">
                                    <div class="installment-select">
                                        <label>Taksit Seç</label>
                                        <div class="yuzde-select-div" id="taksit-select-div"
                                            style="display: table-cell;">

                                <label><input type="radio" class="option-input radio" name="taksit-sayisi" onchange="krediHesapla('108000','252000','6')" value="6">6 Ay</label>
                                <label><input type="radio" class="option-input radio" name="taksit-sayisi" onchange="krediHesapla('108000','252000','12')" value="12" >12Ay</label>
                                <label><input type="radio" class="option-input radio" name="taksit-sayisi" onchange="krediHesapla('108000','252000','18')" value="18">18 Ay</label>
                                <label><input type="radio" class="option-input radio" name="taksit-sayisi" onchange="krediHesapla('108000','252000','24')" value="24" checked="">24 Ay</label>

                                        </div>
                                    </div>
                                </div>
                               </div>

                               <a class="babtn w-100 mt-2" style="background-color: #22242a; color: #fff; cursor: pointer;" onclick="hesaplaButton()">Hesapla</a>

                               <div class="row mt-4">
                                <div class="col-12">
                                    <h5>Sonuç</h5>
                                </div>

                                <div class="col-6">
                                    <b style="color: #22242a;">Peşin Satış Fiyatı</b>
                                </div>
                                <div class="col-6 text-right">
                                    <b style="color: #22242a;" id="pesin_satis_fiyati"><?php echo $fiyat; ?></b>
                                </div>
                                <div class="col-6">
                                    <span>Peşinat</span>
                                </div>
                                <div class="col-6 text-right">
                                    <span id="pesinat">
            <?php                      
    $bul = array(' ',',','.');
    $degistir = array('','','');
    $fiyatx = str_replace($bul, $degistir, $fiyat); // Bu alanda kredi tutarında boşluk virgül veya nokta varsa onları kaldırıyoruz.
                                    
                                     echo $sonuc= $fiyatx *30/100;  ?>
                                    
                                    </span>
                                </div>
                                <div class="col-12 mt-1 mb-1" style="height: 0.5px; background-color: #ddd;"></div>
                                <div class="col-6">
                                    <span>Borç Tutarı</span>
                                </div>
                                <div class="col-6 text-right">
                                    <span id="borc_tutari">
                                    <?php
                                        $bul = array(' ',',','.');
                                        $degistir = array('','','');
                                        $fiyat = str_replace($bul, $degistir, $fiyat);
                                    echo $fiyat - $sonuc ?>
                                    </span>
                                </div>

                                <div class="col-6 mt-3">
                                    <span>Taksit Sayısı</span>
                                </div>
                                <div class="col-6 text-right mt-3">
                                    <span id="taksit_sayisi"></span>
                                </div>
                                <div class="col-6">
                                    <span>Aylık Ödeme Tutarı</span>
                                </div>
                                <div class="col-6 text-right">
                                    <span id="aylik_odeme_tutar"></span>
                                </div>
                                <div class="col-6">
                                    <span>Toplam Borç Tutarı</span>
                                </div>
                                <div class="col-6 text-right">
                                    <span id="toplam_borc_tutari"></span>
                                </div>
                                <div class="col-12 mt-1 mb-1" style="height: 0.5px; background-color: #ddd;"></div>
                                <div class="col-6">
                                    <b style="color: #22242a;">Toplam Ödeme</b>
                                </div>
                                <div class="col-6 text-right">
                                    <b style="color: #22242a;" id="toplam_odeme"></b>
                                </div>
                              
                              
                            </div>
                             </div>