a, x-$\frac{15}{8}$ =$\frac{5}{20}$
x =$\frac{5}{20}$ +$\frac{15}{8}$
x =$\frac{17}{8}$
b,$\frac{-2}{3}$ :x +1=$\frac{-7}{3}$ :2
$\frac{-2}{3}$ :x+ 1 =$\frac{-7}{6}$
$\frac{-2}{3}$ :x =$\frac{-7}{6}$ -1
$\frac{-2}{3}$ :x =$\frac{-13}{6}$
x =$\frac{-2}{3}$ : $\frac{-13}{6}$
x =$\frac{4}{13}$
c,$\frac{-7}{15}$ .x+$\frac{5}{6}$ =$\frac{1}{4}$
$\frac{-7}{15}$ .x =$\frac{1}{4}$ -$\frac{5}{6}$
$\frac{-7}{15}$ .x =$\frac{-7}{12}$
x =$\frac{-7}{12}$ :$\frac{-7}{15}$
x =$\frac{5}{4}$
CHÚC BẠN HỌC TỐT!!!
