$\frac{10x +3}{12} = 1 + \frac{6 +8x}{9}$
$⇔ \frac{9.(10x +3)}{108} = \frac{108}{108} + \frac{12.(6 +8x)}{108}$
$⇔ 9.(10x +3) = 108 + 12.(6 +8x)$
$⇔ 90x +27 = 108 +72 +96x$
$⇔ 90x -96x = 180 -27$
$⇔ -6x = 153$
$⇔ x = \frac{51}{2}$
$ Vậy $ $S$ $=$ {$\frac{51}{2}$}
