Найдите значение выражения а) (4/5-11/5)*5/11 б)7/88*(8/21+8/7) в) 3/7*(1/4+7/12) вот...

а) $( \frac{4}{5} - \frac{11}{5})* \frac{5}{11} = - \frac{7}{5}* \frac{5}{11}= -\frac{7}{11}$
б) $\frac{7}{88}*( \frac{8}{21}+ \frac{8}{7})= \frac{7}{88}*(\frac{8}{21}+ \frac{24}{21}) = \frac{7}{88}* \frac{32}{21} = \frac{1}{11}* \frac{4}{3}= \frac{4}{33}$
в) $\frac{3}{7}*( \frac{1}{4}+ \frac{7}{12})= \frac{3}{7}*( \frac{3}{12}+ \frac{7}{12}) = \frac{3}{7}* \frac{10}{12}= \frac{3}{7}* \frac{5}{6}= \frac{5}{14}$