Tính 5 / 9 + 4 / 3; 6 / 5 - 2 / 3; 15 / 8 x 4 /5

* Hướng dẫn giải

$$\begin{gathered} \frac{5}{9}+\frac{4}{3}=\frac{5}{9}+\frac{12}{9}=\frac{17}{9} \\ \frac{6}{5}-\frac{2}{3}=\frac{18}{15}-\frac{10}{15}=\frac{8}{15} \\ \frac{15}{8}x\frac{4}{5}\mathit{=}\frac{\mathit{15}\mathit{x}\mathit{4}}{\mathit{8}\mathit{x}\mathit{5}}=\frac{\mathit{3}}{\mathit{2}} \\ \frac{6}{7}:\frac{8}{14}=\frac{6x14}{7x8}=\frac{6}{4}=\frac{3}{2} \end{gathered}$$