1. Calculate:Tính:a.$\frac{7}{9}$ x$\frac{4}{5}$b. 2$\frac{1}{4}$ x...

Cách làm chi tiết:

a. $\frac{7}{9}$ x $\frac{4}{5}$ = $\frac{7 x 4}{9 x 5}$ = $\frac{28}{45}$

b. 2 $\frac{1}{4}$ x 3 $\frac{2}{5}$ = $\frac{9}{4}$ x $\frac{17}{5}$ = $\frac{9 x 17}{4 x 5}$ = $\frac{153}{20}$

c. $\frac{1}{5}$ : $\frac{7}{8}$ = $\frac{1}{5}$ x $\frac{8}{7}$ = $\frac{8}{35}$

d. 1 $\frac{1}{5}$ : 1 $\frac{1}{3}$ = $\frac{6}{5}$ : $\frac{4}{3}$ = $\frac{6}{5}$ x $\frac{3}{4}$ = $\frac{18}{20}$

Đáp án:
a. $\frac{28}{45}$
b. $\frac{153}{20}$
c. $\frac{8}{35}$
d. $\frac{18}{20}$