вправа 5 гдз 7 клас алгебра Мерзляк Полонський

Відповідь: \begin{equation}1)14\frac{7}{15}-3\frac{3}{23}·\frac{23}{27}-1\frac{1}{5}·\frac{1}{6}=\end{equation} \begin{equation}=14\frac{7}{15}-\frac{72}{23}·\frac{23}{27}-\frac{6}{5}·\frac{1}{6}=\end{equation} \begin{equation}=14\frac{7}{15}-\frac{8}{3}-\frac{1}{5}=\end{equation} \begin{equation}=14\frac{7}{15}-2\frac{2}{3}-\frac{1}{5}=\end{equation} \begin{equation}=11\frac{22-2·5-1·3}{15}=\end{equation} \begin{equation}=11\frac{9}{15}=11\frac{3}{5};\end{equation} \begin{equation}2)\left ( 5\frac{8}{9}:1\frac{17}{36}+1\frac{1}{4} \right )·\frac{5}{21}=\end{equation} \begin{equation}=\left ( \frac{53}{9}:\frac{53}{36}+1\frac{1}{4} \right )·\frac{5}{21}=\end{equation} \begin{equation}=\left ( \frac{53}{9}·\frac{36}{53}+1\frac{1}{4} \right )·\frac{5}{21}=\end{equation} \begin{equation}=\left ( 4+1\frac{1}{4} \right )·\frac{5}{21}=5\frac{1}{4}·\frac{5}{21}=\end{equation} \begin{equation}\frac{21}{4}·\frac{5}{21}=\frac{5}{4}=1\frac{1}{4};\end{equation} 3) (-3,25 - 2,75) : (-0,6) + 0,8 · (-7) =
=(-6) : (-0,6) - 5,6 = 10 - 5,6 = 4,4; \begin{equation}4)\left ( -1\frac{3}{8}-2\frac{5}{12} \right ):5\frac{5}{12}=\end{equation} \begin{equation}=-3\frac{3·3+5·2}{24}:5\frac{5}{12}=\end{equation} \begin{equation}=-3\frac{19}{24}:5\frac{5}{12}=\end{equation} \begin{equation}=-\frac{91}{24}:\frac{65}{12}=-\frac{7·13}{2·12}·\frac{12}{5·13}=\end{equation} \begin{equation}=-\frac{7}{2}·\frac{1}{5}=-\frac{7}{10}.\end{equation}