$\frac{x}{3}$ = x + $\frac{13}{4}$
4x = 52x + 269
4x - 52x = 169
-48x = 169
x = -$\frac{169}{48}$
Vậy x = -$\frac{169}{48}$
b. $\frac{14}{x-3}$ = $\frac{13}{x+1}$
$\frac{14}{x-3}$ = $\frac{13}{x+1}$ , x $\neq$ 3, x \neq$ -1
14(x+1) = 13(x-3)
14x + 14 = 13x -39
14x - 13x = -39 - 14
x = -53, x $\neq$ 3, x x \neq$ -1
Vậy x = -53