sum textbox value with gridview column value.

Question

I want to sum Textbox value with gridview column credit value as in image,i highlighted Credit total 5000 with textbox(txtamount).

 <script type="text/javascript">
        $(function () {
            $(".js-example-placeholder-single").select2({
                placeholder: "Select",
                allowClear: true
            });
        });

         //On UpdatePanel Refresh
    var prm = Sys.WebForms.PageRequestManager.getInstance();
    if (prm != null) {
        prm.add_endRequest(function (sender, e) {
            if (sender._postBackSettings.panelsToUpdate != null) {
               $(".js-example-placeholder-single").select2({
                  placeholder: "Select",
                  allowClear: true
               });
                 $(function () {
        CalculateDebitCredittotal()
    });
            }
        });
    };

     $(function () {
        CalculateDebitCredittotal()
    });
 
    function CalculateDebitCredittotal() {
        var creditTotal = 0;
        var debitTotal = 0;

         
 

        $("[id*=gvtrans] tr:has(td)").each(function () {
        
            if ($(this).find($("[id*=txtCredit]")).val() != "" && $(this).find($("[id*=txtCredit]")).val() != undefined)

            {
                creditTotal += parseFloat($(this).find($("[id*=txtCredit]")).val());
            }
           
            if ($(this).find($("[id*=txtDebit]")).val() != "" && $(this).find($("[id*=txtDebit]")).val() != undefined)
            {
                debitTotal += parseFloat($(this).find($("[id*=txtDebit]")).val());
            }

            $(this).find($("[id*=lblTotaldr]")).html("Total:" + debitTotal.toString());
            $(this).find($("[id*=lblTotalcr]")).html("Total:" + creditTotal.toString() );
        });


        $("[id*=hfCredit]").val(creditTotal);
        $("[id*=hfDebit]").val(debitTotal);
    }
    </script>

 
<asp:TextBox ID="txtamount" Text="" runat="server" AutoPostBack="true" ></asp:TextBox>                 <asp:Button ID="btn_add" runat="server"  OnClick="btn_add_Click" Text="Add" Width="66px" style="position:relative; float:right; border:none; margin-right:20px; background-color: #CCFFCC;" CssClass="auto-style5" />                 <asp:HiddenField ID="hfDebit" runat="server" />                 <asp:HiddenField ID="hfCredit" runat="server" />

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
                      
     <asp:UpdatePanel runat="server" ID="UP_MainList" UpdateMode="Conditional">
        <ContentTemplate>
                <asp:GridView ID="gvtrans" runat="server" AllowSorting="True" AutoGenerateColumns="False"  BackColor="#99ccff" HeaderStyle-ForeColor="#ccffff"  
                   OnRowDataBound="gvtrans_RowDataBound" OnRowDeleting="gvtrans_RowDeleting" ShowFooter="True" ShowHeaderWhenEmpty="True" CssClass="table table-responsive"  >
                
                    <Columns>
                        <asp:BoundField DataField="RowNumber" HeaderText="S.NO"  />
                        <asp:TemplateField HeaderText="Code" >
                            <ItemTemplate>
                                <asp:TextBox ID="txtcode" runat="server"></asp:TextBox>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Head" >
                            <ItemTemplate>
                                <asp:Label ID="lbfourdr" runat="server" Visible="false" />
                                <asp:DropDownList ID="ddlfourdr" runat="server" AutoPostBack="true" CssClass="form-control js-example-placeholder-single" Height="85px" OnSelectedIndexChanged="ddlfourdr_SelectedIndexChanged" ToolTip="Select " Width="300px">
                                </asp:DropDownList>
                            </ItemTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Debit">
                            <ItemTemplate>
                                <asp:TextBox ID="txtDebit" runat="server" AutoPostBack="true" ></asp:TextBox>
                            </ItemTemplate>
                            <FooterTemplate>
                                <asp:Label ID="lblTotaldr" runat="server" ></asp:Label>
                            </FooterTemplate>
                        </asp:TemplateField>
                      

                          <asp:TemplateField HeaderText="Credit">
                            <ItemTemplate>
                                <asp:TextBox ID="txtCredit" runat="server" AutoPostBack="true"   ></asp:TextBox>
                            </ItemTemplate>
                            <FooterTemplate>
                                <asp:Label ID="lblTotalcr" runat="server"></asp:Label>
                            </FooterTemplate>
                        </asp:TemplateField>
                        <asp:TemplateField HeaderText="Description" >
                            <ItemTemplate>
                                <asp:TextBox ID="txtremarks" runat="server"></asp:TextBox>
                            </ItemTemplate>
                        </asp:TemplateField>
                    
                        <asp:CommandField ButtonType="Button" ControlStyle-ForeColor="Red" ShowDeleteButton="True" />
                    </Columns>
                  
                </asp:GridView>
             </ContentTemplate>

        </asp:UpdatePanel>