\[\boxed{\mathbf{37}.}\]
\[1)\ 7x + 2 - ax = 2 \cdot (x + 1)\]
\[7x + 2 - ax = 2x + 2\]
\[5x - ax = 0\]
\[x(5 - a) = 0\]
\[5 - a = 0\]
\[a = 5.\]
\[Ответ:при\ a = 5.\]
\[2)\ (3 - a)x + 4x = 2 - 5x\]
\[3x - ax + 4x + 5x = 2\]
\[12x - ax = 2\]
\[x(12 - a) = 2\]
\[такого\ значения\ a\ не\]
\[\ существует.\]
\[Ответ:\text{a\ }не\ существует.\]