JSFiddle - React, Tailwind, and code Playground

HTML

<form>
        <table align="center">
            <tr>
                <td colspan="3" align="center"><img src="" title="img-title" /></td>
            </tr>
            <tr>
                <td colspan="3"><br/></td>
            </tr>
            <tr>
                <td align="center">Quantity:</td>
                <td colspan="2"></td>
            </tr>
            <tr>
                <td><input type="number" min="64" max="9999" name="quantity" value="64" /></td>
                <td>20/per item
                <input type="hidden" name="price" value="20" /></td>
                <td id="total-price">Total Goes Here</td>
            </tr>
        </table>
    </form>

JavaScript

$(document).ready(function() {
    var calcTotal = function(el) {
        var quantity = el.val();
        var price = $('[name="price"]').val();
        var total = quantity * price;
        $('#total-price').html(total);
    };
    
    calcTotal($('[name="quantity"]'));
    
    $('[name="quantity"]').on('change', function() {
		calcTotal($(this));
    });

});