a,$\frac{8}{5}$+ $\frac{3}{10}$ =$\frac{16}{10}$ +$\frac{3}{10}$ =$\frac{19}{10}$
b,$\frac{2}{3}$+ $\frac{3}{4}$+ $\frac{1}{6}$ =$\frac{8}{12}$+ $\frac{39}{12}$+ $\frac{2}{12}$=$\frac{49}{12}$
c,$\frac{5}{6}$- $\frac{2}{9}$ =$\frac{45}{54}$- $\frac{12}{54}$ =$\frac{33}{54}$ =$\frac{11}{18}$
d,2$\frac{1}{10}$- $\frac{3}{4}$- $\frac{2}{5}$ =$\frac{21}{10}$- $\frac{3}{4}$- $\frac{2}{5}$= $\frac{42}{20}$- $\frac{15}{20}$- $\frac{8}{20}$=$\frac{19}{20}$
