\[ -2 \cdot 5 - (-2) \cdot 3x = 7x + 3 \]
\[ -10 + 6x = 7x + 3 \]
\[ 6x - 7x = 3 + 10 \]
\[ -x = 13 \]
\[ x = -13 \]
Ответ: -13