Tính. 1/6 : 3/7

a) $\frac{1}{6}:\frac{3}{7}$

b) $\frac{5}{12}:\frac{1}{4}$

c) $\frac{4}{15}:\frac{8}{3}$

d) $\frac{18}{5}:\frac{9}{10}$

a) $\frac{1}{6}:\frac{3}{7}$ = $\frac{1}{6}\times \frac{7}{3}$ = $\frac{7}{18}$

b) $\frac{5}{12}:\frac{1}{4}$ = $\frac{5}{12}\times \frac{4}{1}$ = $\frac{20}{12}=\frac{5}{3}$

c) $\frac{4}{15}:\frac{8}{3}$ = $\frac{4}{15}\times \frac{3}{8}$ = $\frac{12}{120}$ = $\frac{1}{12}$

d) $\frac{18}{5}:\frac{9}{10}$ = $\frac{18}{5}\times \frac{10}{9}=\frac{180}{45}=4$