\[\boxed{\mathbf{228\ (228)}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
Пояснение.
Решение.
\[\frac{2 \cdot 2}{y \cdot 2} = \frac{4}{2y}\text{\ \ \ \ \ \ }\]
\[\frac{4}{2y} = \frac{x}{6}\text{\ \ }\]
\[x = 4.\ \ \ \ \ \ \]
\[2y = 6\]
\[y = 6\ :2\]
\[y = 3.\]
\[Ответ:x = 4;\ \ y = 3.\]
\[\boxed{\mathbf{228\ (}\mathbf{с}\mathbf{)}\mathbf{.}\mathbf{\ }Еуроки\ - \ ДЗ\ без\ мороки}\]
Пояснение.
Решение.
\[\frac{b \cdot 3}{4 \cdot 3} = \frac{3b}{12}\text{\ \ \ \ \ }\]
\[\frac{3b}{12} = \frac{21}{a}\ \]
\[a = 12.\ \ \ \]
\[3b = 21\]
\[b = 21\ :3\]
\[b = 7.\]
\[\boxed{\mathbf{228}\mathbf{.}}\]
\[BD = 4 \cdot 2 = 8\ см.\]
\[AE = 25\ см.\]
\[AB + DE = AE - BD =\]
\[= 25 - 8 = 17\ см.\]
\[Ответ:17\ см.\]