Tính:

* Hướng dẫn giải

 $$\begin{gathered} a) \frac{1}{2}+\frac{3}{4}=\frac{2}{4}+\frac{3}{4}=\frac{5}{4} \\ b) \frac{3}{5}-\frac{3}{8}=\frac{24}{40}-\frac{15}{40}=\frac{9}{40} \\ c) \frac{3}{10}\times \frac{4}{9}=\frac{3\times 4}{10\times 9}=\frac{1\times 2}{5\times 3}=\frac{2}{15} \\ d) \frac{5}{8}:\frac{3}{2}=\frac{5}{8}\times \frac{2}{3}=\frac{5\times 2}{8\times 3}=\frac{5\times 1}{4\times 3}=\frac{5}{12} \end{gathered}$$