Tính :

* Hướng dẫn giải

a. $4+\frac{5}{4}=\frac{4}{1}+\frac{5}{4}=\frac{16}{4}+\frac{5}{4}=\frac{21}{4}$

b. $\frac{3}{4}+\frac{1}{3}=\frac{9}{12}+\frac{4}{12}=\frac{13}{12}$

c. $\frac{2}{3}+\frac{7}{15}-\frac{3}{5}=\frac{10}{15}+\frac{2}{15}-\frac{9}{15}=\frac{10+7-9}{15}=\frac{8}{15}$

d. $\frac{13}{6}+\frac{5}{3}-2=\frac{13}{6}+\frac{10}{6}-\frac{12}{6}=\frac{13+10-12}{6}=\frac{11}{6}$