Найдите значение выражения 8 7\10-(7 4\5-а) при а=6 1\2 14 1\6-(8 9\10-b) при b=5 2\3...

Решите задачу:

$1. \ 8 \frac{7}{10}-(7 \frac{4}{5}-a); \ a=6; \\ 8 \frac{7}{10}-(7 \frac{4}{5}-6)=8 \frac{7}{10}-(6 \frac{9}{5}-5 \frac{5}{5} )= \\ 8 \frac{7}{10}-1 \frac{4}{5}=8,7-1,8=7,9; \\ 2. \ \frac{1}{6}-(8 \frac{9}{10}-b) ; b=5 \frac{2}{3}; \\ \frac{1}{6}-(8 \frac{9}{10}-5 \frac{2}{3})= \frac{1}{6}-(\frac{89}{10}-\frac{17}{3})= \\ \frac{1}{6}-(\frac{3*89}{30}-\frac{17*10}{30})= \frac{5}{30}-(\frac{267}{30}-\frac{170}{30})=\frac{5}{30}-\frac{97}{30}= -3\frac{7}{30}$
$3. \ a- (9\frac{3}{50}-5 \frac{7}{25}); a=7 \frac{1}{2}; \\ 7,5-(9,06-5,28)=7,5-3,78=3,72$
$4. \ (20 \frac{1}{5}-b)-6 \frac{1}{3}; b=11 \frac{2}{15}; \\ (20\frac{1}{5}-11\frac{2}{15})-6\frac{1}{3}= \ (20\frac{3}{15}-11\frac{2}{15})-6\frac{5}{15}= \\ = 9\frac{1}{15} -6 \frac{5}{15}= 2\frac{10}{15}=2 \frac{2}{3}$