\[\boxed{\mathbf{Страница}\mathbf{\ \ 15}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
\[\boxed{\mathbf{11}\mathbf{.}\mathbf{\ }}\]
\[15 \cdot 2 = 15 + 15 = 30\]
\[12 \cdot 5 =\]
\[= 12 + 12 + 12 + 12 + 12 = 60\]
\[10 \cdot 7 =\]
\[= 10 + 10 + 10 + 10 + 10 + 10 + 10 =\]
\[= 70\]
\[8 \cdot 4 = 8 + 8 + 8 + 8 = 32\]
\[\boxed{\mathbf{12}\mathbf{.}}\]
\[1)\ 28 + 17 = 45\ (кг) - огурцов\ \]
\[собрали\ с\ другой\ грядки.\]
\[2)\ 28 + 45 = 73\ (кг) - огурцов\ \]
\[собрали\ всего.\]
\[3)\ 73 - 39 = 34\ (кг) - огурцов\ \]
\[оставили.\]
\[Ответ:34\ кг.\]
\[\boxed{\mathbf{13}\mathbf{.}\mathbf{\ }}\]
\[5 \cdot 9 = 45\]
\[45\ :5 = 9\]
\[45\ :9 = 5\]
\[10 \cdot 4 = 40\]
\[40\ :10 = 4\]
\[40\ :4 = 10\]
\[6 \cdot 3 = 18\]
\[18\ :6 = 3\]
\[18\ :3 = 6\]
\[\boxed{\mathbf{14}\mathbf{.}\mathbf{\ }}\]
\[3 \cdot 5 < 5 + 5 + 5 + 5 + 5\]
\[19 + 19 + 19 + 19 = 19 \cdot 4\]
\[7 \cdot 4 > 7 + 7 + 7\]
\[45 + 45 + 45 > 45 \cdot 2\]
\[\boxed{\mathbf{15}\mathbf{.}\mathbf{\ }}\]
\[27\ :x = 9\]
\[x = 3.\]
\[5 \cdot x = 30\]
\[x = 6.\]
\[x\ :6 = 3\]
\[x = 18.\]