$a) \frac{5x -6}{7} - \frac{3x +1}{4} = \frac{x +16}{5}$
$⇔ \frac{20(5x -6)}{140} - \frac{35(3x +1)}{140} = \frac{28(x +16)}{140}$
$⇔ 20(5x -6) - 35(3x +1) = 28(x +16)$
$⇔ 100x -120 -105x -35 = 28x +448$
$⇔ -33x = 603$
$⇔ x = \frac{-201}{11}$
$Vậy$ $S =$ {$ \frac{201}{11}$}
$b) \frac{x +5}{4} - \frac{2x -5}{3} = \frac{6x -1}{3} + \frac{2x -3}{6}$
$⇔ \frac{3(x +5)}{12} - \frac{4(2x -5)}{12} = \frac{4(6x -1)}{12} + \frac{2(2x -3)}{12}$
$⇔ 3(x +5) - 4(2x -5) = 4(6x -1) + 2(2x -3)$
$⇔ 3x +15 -8x +20 = 24x -4 +4x -6$
$⇔ -33x = -45$
$⇔ x = \frac{15}{11}$
$Vậy$ $S =$ {$\frac{15}{11}$}
$c) 1 - \frac{2x -1}{9} = \frac{x}{2} - \frac{13x -10}{6}$
$⇔ \frac{18}{18} - \frac{2(2x -1)}{18} = \frac{9x}{18} - \frac{3(13x -10)}{18}$
$⇔ 18 -2(2x -1) = 9x -3(13x -10)$
$⇔ 18 -4x +2 = 9x -39x +30$
$⇔ 26x = 10$
$⇔ x = \frac{5}{13}$
$Vậy$ $S =$ {$\frac{5}{13}$}
