<!Doctype html>
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
</head>
<body>
<table>
<tr>
<td><input type="number" class="product-buying-price"></td>
<td><input type="number" class="product-selling-price"></td>
<td class="net-profit"></td>
</tr>
</table>
<script>
$('.product-buying-price, .product-selling-price').on('blur', function(e) {
var row = $(this).closest('tr');
var buying_pr = $('.product-buying-price', row),
selling_pr = $('.product-selling-price', row),
net_profit = $('.net-profit', row);
buy_pr = parseFloat(buying_pr.val());
sell_pr = parseFloat(selling_pr.val());
if (!isNaN(buy_pr) && !isNaN(sell_pr)) {
net_profit.text((sell_pr - buy_pr).toFixed(2));
}
});
</script>
</body>
</html>