Вычисли выражения: а) 1 2/5 + (2 1/5 + 1/5)

- a) $1\frac{2}{5} + (2\frac{1}{5} + \frac{1}{5}) = 1\frac{2}{5} + 2\frac{2}{5} = 3\frac{4}{5}$ - б) $3 - (\frac{2}{7} + \frac{3}{7}) = 3 - \frac{5}{7} = 2\frac{2}{7}$ - в) $4\frac{5}{7} - (1\frac{3}{7} - \frac{2}{7}) = 4\frac{5}{7} - 1\frac{1}{7} = 3\frac{4}{7}$ - г) $1\frac{1}{4} + (2\frac{3}{4} - 1\frac{2}{4}) = 1\frac{1}{4} + 1\frac{1}{4} = 2\frac{2}{4} = 2\frac{1}{2}$ - д) $4\frac{2}{3} + (2\frac{2}{3} - \frac{2}{3}) = 4\frac{2}{3} + 2 = 6\frac{2}{3}$ - 1) $0,0165 : 0,0055 = 165 : 55 = 3$ - 2) $0,0609 : 0,001 = 60,9$ - 3) $78,32 : 88 = 0,89$ $$\begin{array}{cc|l} 78, & 32 & 88 \ \hline & & 0,89 \ \end{array}$$ - 4) $91 : 2,8 = 32,5$ $$\begin{array}{ccc|l} 91, & 0 & & 2,8 \ \hline 84 & & & 32,5 \ \hline 7 & 0 \\ 5 & 6 \hline 1 & 40 \end{array}$$ - 5) $156,375 : 6,25 = 24,0$ $$\begin{array}{cccc|l} 156, & 375 & & 6,25 \ \hline 125 & 0 & & 24,0 \ \hline 31 & 37 \\ & & & \ \end{array}$$ **Ответы:** - a) $3\frac{4}{5}$ - б) $2\frac{2}{7}$ - в) $3\frac{4}{7}$ - г) $2\frac{1}{2}$ - д) $6\frac{2}{3}$ - 1) $3$ - 2) $60,9$ - 3) $0,89$ - 4) $32,5$ - 5) $25,02$