25. Найдите значение выражения: а) 25 · (7/10 + 3/5 + 1/2); б) (5/12 + 1/6 + 3/8) : 15/16; в) 5 : 1 1/4 + 7 : 1 1/3; г) 1/2 + 3/4 · 8/15 − 3/10.

а) \(25\cdot\left(\frac{7}{10}+\frac{3}{5}+\frac{1}{2}\right)=25\cdot\left(\frac{7}{10}+\frac{6}{10}+\frac{5}{10}\right)=25\cdot\frac{18}{10}=25\cdot\frac{9}{5}=45\).

б) \(\left(\frac{5}{12}+\frac{1}{6}+\frac{3}{8}\right):\frac{15}{16}=\left(\frac{10}{24}+\frac{4}{24}+\frac{9}{24}\right)\cdot\frac{16}{15}=\frac{23}{24}\cdot\frac{16}{15}=\frac{46}{45}\).

в) \(5:1\frac{1}{4}+7:1\frac{1}{3}=5:\frac{5}{4}+7:\frac{4}{3}=4+\frac{21}{4}=\frac{37}{4}=9\frac{1}{4}\).

г) \(\frac{1}{2}+\frac{3}{4}\cdot\frac{8}{15}-\frac{3}{10}=\frac{1}{2}+\frac{2}{5}-\frac{3}{10}=\frac{5}{10}+\frac{4}{10}-\frac{3}{10}=\frac{3}{5}\).

Ответ: а) 45; б) \(\frac{46}{45}\); в) \(\frac{37}{4}=9\frac{1}{4}\); г) \(\frac{3}{5}\).