Tính:

$$\begin{gathered} a)\hspace{0.17em}\frac{9}{14}-\frac{4}{7}=\mathrm{..........................................} \\ b)\hspace{0.17em}\frac{2}{5}-\frac{4}{15}=\mathrm{..........................................} \\ c) \frac{8}{7}-\frac{10}{21}=\mathrm{..........................................} \end{gathered}$$

Rút gọn rồi tính:

$$\begin{gathered} a)\hspace{0.17em}\frac{8}{18}+\frac{5}{3}=.......................................... \\ b)\hspace{0.17em}\frac{20}{15}-\frac{4}{45}=\mathrm{..........................................} \end{gathered}$$

Rút gọn rồi tính:

$$\begin{gathered} a)\hspace{0.17em}\frac{8}{24}+\frac{4}{48}=\mathrm{..........................................} \\ b)\hspace{0.17em}\frac{40}{32}-\frac{1}{2}=\mathrm{..........................................} \end{gathered}$$

Tính: 

$$\begin{gathered} a)\hspace{0.17em}\frac{1}{4}+\frac{3}{8}=\mathrm{..........................................} \\ b) \frac{5}{12}+\frac{7}{3}=\mathrm{..........................................} \\ c)\hspace{0.17em}\frac{3}{16}+\frac{9}{4}=\mathrm{..........................................} \end{gathered}$$

Tính (theo mẫu): 

Mẫu: $4+\frac{2}{5}=\frac{4}{1}+\frac{2}{5}=\frac{20}{5}+\frac{2}{5}=\frac{22}{5}$

Ta có thể viết gọn như sau:

$5+\frac{3}{2}$ = ………………………………………

$\frac{3}{4}+2$ = ………………………………………

$\frac{8}{9}+3$ = ………………………………………