Найдите значение выражения: а) 61/64 - (7/12 - 5/14) * (13/16 + 1/2); б) (1 - 11/17) * (3/4 - 5/12 + 11/18); в) 1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6; г) 1/8 + 3/8 + 1/12 + 5/12 + 1/16 + 7/16 + 1/20 + 9/20.

а) $\frac{61}{64}-\left(\frac{7}{12}-\frac{5}{14}\right)\cdot\left(\frac{13}{16}+\frac{1}{2}\right)=\frac{61}{64}-\left(\frac{49-30}{84}\right)\cdot\left(\frac{13+8}{16}\right)=\frac{61}{64}-\frac{19}{84}\cdot\frac{21}{16}=\frac{61}{64}-\frac{19}{4\cdot16}=\frac{61}{64}-\frac{19}{64}=\frac{42}{64}=\frac{21}{32}$ б) $\left(1-\frac{11}{17}\right)\cdot\left(\frac{3}{4}-\frac{5}{12}+\frac{11}{18}\right)=\frac{6}{17}\cdot\left(\frac{27-15+22}{36}\right)=\frac{6}{17}\cdot\frac{34}{36}=\frac{1\cdot2}{1\cdot6}=\frac{1}{3}$ в) $1-\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}=\frac{1}{2}+\frac{1}{3}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}=\frac{5}{6}-\frac{1}{4}+\frac{1}{5}-\frac{1}{6}=\left(\frac{5}{6}-\frac{1}{6}\right)-\frac{1}{4}+\frac{1}{5}=\frac{4}{6}-\frac{1}{4}+\frac{1}{5}=\frac{2}{3}-\frac{1}{4}+\frac{1}{5}=\frac{8-3}{12}+\frac{1}{5}=\frac{5}{12}+\frac{1}{5}=\frac{25+12}{60}=\frac{37}{60}$ г) $\frac{1}{8}+\frac{3}{8}+\frac{1}{12}+\frac{5}{12}+\frac{1}{16}+\frac{7}{16}+\frac{1}{20}+\frac{9}{20}=\frac{4}{8}+\frac{6}{12}+\frac{8}{16}+\frac{10}{20}=\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}=2$ **Ответ:** а) $\frac{21}{32}$; б) $\frac{1}{3}$; в) $\frac{37}{60}$; г) $2$.