Question

помогите пожалуйста

Answer 1

$\frac{1}{4}+ \frac{1}{5}= \frac{5}{20} + \frac{4}{20} = \frac{9}{20} \\ \frac{1}{8}+ \frac{1}{7}= \frac{7}{56} + \frac{8}{56}= \frac{15}{56} \\ \frac{3}{5} + \frac{3}{4}= \frac{12}{20} + \frac{15}{20} = \frac{27}{20}= 1\frac{7}{20}$