Sum of two jquery values using foreach in php

I am stuck with a problem that I have not been able to solve, I am using a form and in the view I have a foreach running through an array. The problem I have is that I need to return the total of the sum between the value-a and value-b and the result in an input sum_total but the value is repeated because I am selecting the class, I tried to place the button that performs the action outside the loop but it has not worked for me. I attach my php and jquery code. I appreciate the help

<?php

//Get work order
$workerItem = "work_id";
$workerValue = $_GET["workId"];

$worker = WorkordersController::ctlWorkShow($workerItem,$workerValue);

//Decode json string
$workersList = json_decode($worker["work_workers"],true);

foreach ($workersList as $key => $value) {

    $item = "user_id";
    $value_2 = $value["id"];

    $response = UsersController::ctlUserShow($item, $value_2);

    echo '<div class="row" style="padding:5px 15px">
            <div class="col-xs-3" style="padding-right: 0px" >
              <div class="input-group">

                <input type="text" style="font-size: 12px" class="form-control newWorkerName"    value="'.($key+1).'" readonly >
            </div>
           </div>
           <div class="col-xs-3" >
               <div class="input-group">
                   <input type="text" style="font-size: 12px" class="form-control valor-a"  value="" >
               </div>
           </div>

           <div class="col-xs-3" >
               <div class="input-group">
                   <input type="text" style="font-size: 12px" class="form-control valor-b"  value="" >
               </div>
           </div>

           <div class="col-xs-3" style="padding-left: 0px">
               <div class="input-group">
                   <input type="text" style="font-size: 12px" class="form-control suma_total" value="" readonly>
               </div>
            </div>
        </div>';
}

echo '<button class="btn btn-success btnCalcular" style="font-size: 11px">Calcular</button>';
?>

$(".btnCalcular").click(function () {

  event.preventDefault();

  var valorA = $(".valor-a").val();

  var valorB = $(".valor-b").val();

  var total = $(".suma_total");

  var suma = Number(valorA)+Number(valorB);

  total.val(suma);

});