\[\boxed{\text{1215\ (1215).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[(5 - a)x + a = \text{ax} + 2,\]
\[\text{\ \ }x = - 3\]
\[- 3 \cdot (5 - a) + a = - 3a + 2\]
\[- 15 + 3a + a = - 3a + 2\]
\[7a = 17\]
\[a = \frac{17}{7}\]
\[y = ax + 2:\ \]
\[y = \frac{- 3 \cdot 17}{7} + 2 = - \frac{51}{7} + 2 =\]
\[= - \frac{37}{7} = - 5\frac{2}{7}.\]
\[Ответ:\ y = - 5\frac{2}{7}\text{.\ }\]