50 баллов помогите плиз

А)
b+c
$\frac{1}{10}+ \frac{2}{5}= \frac{1+4}{10}= \frac{5}{10}= \frac{1}{2}$

c
$\frac{1}{2}- \frac{1}{3}= \frac{3-2}{6}= \frac{1}{6}$

b
$\frac{1}{4}- \frac{1}{5}= \frac{5-4}{20}= \frac{1}{20}$

б)
b-c
$\frac{1}{2}- \frac{1}{7}= \frac{7-2}{14}= \frac{5}{14}$

c
$\frac{5}{8}- \frac{1}{4}= \frac{5-2}{8}= \frac{3}{8}$

b
$\frac{1}{5}+ \frac{1}{2}= \frac{2+5}{10}= \frac{7}{10}$