Выполнить действия 1/2-5/12= 1/8+7/12= 23/40-3/8= 9/35-3/28= решите пожалуйста

1) $\frac{1}{2}- \frac{5}{12} = \frac{1*6}{2*6} - \frac{5}{12} = \frac{6}{12} - \frac{5}{12}= \frac{6-5}{12}= \frac{1}{12}$
2) $\frac{1}{8}+ \frac{7}{12}= \frac{1*3}{8*3}+ \frac{7*2}{12*2}= \frac{3}{24}+ \frac{14}{24}= \frac{3+14}{24}= \frac{17}{24}$
3) $\frac{23}{40}- \frac{3}{8}= \frac{23}{40}- \frac{3*5}{8*5}= \frac{23}{40}- \frac{15}{40}= \frac{23-15}{40}= \frac{8}{40}= \frac{1*8}{5*8}= \frac{1}{5}$
4) $\frac{9}{35}-\frac{3}{28}= \frac{9*4}{35*4}- \frac{3*5}{28*5}= \frac{36}{140}- \frac{15}{140} = \frac{36-15}{140} = \frac{21}{140} = \frac{3*7}{20*7}= \frac{3}{20}$