JSFiddle - React, Tailwind, and code Playground

HTML

<table>     
<tr class="Violão">
    <td>Violão</td>
    <td class="td2 8">8</td>
</tr>
<tr class="Violão">
    <td>Violão</td>
    <td class="td2 23">23</td>
</tr class="Violão">
<tr class="Guitarra">
    <td>Guitarra</td>
    <td class="td2 16">16</td>
</tr>
</table>

JavaScript

$(document).ready(function(){
var total = 0;
$('.td2').each(function(){
    total += parseInt($(this).text());    
});

var totalrow = $('<tr><td>total</td><td>'+total+'</td></tr>');
$('table').append(totalrow);
});