\[\boxed{\mathbf{Страница}\mathbf{\ \ 70}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\boxed{\mathbf{1}\mathbf{.}}\]
\[\boxed{\mathbf{2}\mathbf{.}\mathbf{\ }}\]
\[56\ :7 + x = 7 \cdot 6\]
\[8 + x = 42\]
\[x = 42 - 8\]
\[x = 34\]
\[\overline{56\ :7 + 34 = 7 \cdot 6}\]
\[8 + 34 = 42\]
\[42 = 42.\]
\[a - 81\ :9 = 17\]
\[a - 9 = 17\]
\[a = 17 + 9\]
\[a = 26\]
\[\overline{26 - 81\ :9 = 17}\]
\[26 - 9 = 17\]
\[17 = 17.\]
\[\boxed{\mathbf{3}\mathbf{.}\mathbf{\ }}\]
\[5\ :1 \cdot 6 = 30\ (рублей) - цена\ \]
\[тетради.\]
\[Ответ:30\ рублей.\]
\[\boxed{\mathbf{4}\mathbf{.}\mathbf{\ }}\]
\[7 \cdot 6 - 40 = 2\]
\[3 \cdot 3 + 5 \cdot 7 = 44\]
\[9 \cdot 9 - 8 \cdot 8 = 17\]
\[7 \cdot 8 - 3 \cdot 4 = 44\]