a,$\frac{-2}{15}$ – x = $\frac{-3}{10}$ b,x + $\frac{1}{3}$ = $\frac{2}{5}$ – ( -1/3 ) c, $\frac{3}{7}$ – x = $\frac{1}{4}$ – ( -3/5)

Đáp án:

a, $\frac{-2}{15}$ – x = $\frac{-3}{10}$ 

⇔ x = $\frac{-2}{15}$ – $\frac{-3}{10}$ 

⇔ x = $\frac{-2}{15}$ + $\frac{3}{10}$ 

⇔ x = $\frac{1}{6}$

b, x + $\frac{1}{3}$ = $\frac{2}{5}$ – ( -$\frac{1}{3}$)

⇔ x + $\frac{1}{3}$ = $\frac{2}{5}$ + $\frac{1}{3}$

⇔ x + $\frac{1}{3}$ = $\frac{6}{15}$ + $\frac{5}{15}$ =$\frac{11}{15}$ 

⇔ x = $\frac{11}{15}$  – $\frac{1}{3}$ 

⇔ x = $\frac{2}{5}$

c,  $\frac{3}{7}$ – x = $\frac{1}{4}$ – ( – $\frac{3}{5}$ )

⇔ $\frac{3}{7}$ – x  = $\frac{1}{4}$  + $\frac{3}{5}$

⇔ $\frac{3}{7}$ – x  = $\frac{17}{20}$

⇔ x = $\frac{3}{7}$ – $\frac{17}{20}$

⇔ x = $\frac{-59}{140}$