<tfoot>
<td class="text-right big">Итого:</td>
<td id='cena'><input type="text" readonly="readonly" class="total" name="itogo" value="0"> <i class="fas fa-ruble-sign"></i></td>
</tfoot>
<div class="but-box">
<button type='submit' class="succes mybtn">Отправить</button>
</div>