Tính: 4/3 : 2/5

Lời giải

a) \(\frac{4}{3}:\frac{2}{5} = \frac{4}{3} \times \frac{5}{2} = \frac{{2 \times \bcancel{2} \times 5}}{{3 \times \bcancel{2}}} = \frac{{10}}{3}\)  \(\frac{1}{8}:7 = \frac{1}{8}:\frac{7}{1} = \frac{1}{8} \times \frac{1}{7} = \frac{1}{{56}}\)

b) \(3:\frac{4}{5} = \frac{3}{1} \times \frac{5}{4} = \frac{{3 \times 5}}{{1 \times 4}} = \frac{{15}}{4}\)   \(\frac{4}{5}:3 = \frac{4}{5}:\frac{3}{1} = \frac{4}{5} \times \frac{1}{3} = \frac{4}{{15}}\)