tính a. 1+3/4; b. 4/5-3/8;c.1:2/3;

* Hướng dẫn giải

$$\begin{gathered} a)1+\frac{3}{4}=\frac{4}{4}+\frac{3}{4}=\frac{7}{4} \\ b)\frac{4}{5}-\frac{3}{8}=\frac{32}{40}-\frac{15}{40}=\frac{17}{40} \end{gathered}$$

$$\begin{gathered} c)1:\frac{2}{3}=1\times \frac{3}{2}=\frac{3}{2} \\ d)\frac{2}{5}\times \frac{5}{2}=\frac{10}{10}=1 \end{gathered}$$