a, $12x+\frac{5}{3}=x-2x-$ $\frac{7}{4}$
$<=>$ $12x+\frac{5}{3}=-x-$ $\frac{7}{4}$
$<=>$ $12x+\frac{5}{3}+x=$ $-\frac{7}{4}$
$<=>$ $13x+\frac{5}{3}=$ $-\frac{7}{4}$
$<=>$ $13x=-\frac{7}{4}-$ $\frac{5}{3}$
$<=>$ $13x=-\frac{41}{12}$
$<=>$ $x=-\frac{41}{12}:13$
$=>$ $x=-\frac{41}{156}$
Vậy $x=-\frac{41}{156}$