Решение:
\[ 5x = (4x + 3x) + 14 \]
\[ 5x = 7x + 14 \]
\[ 5x - 7x = 14 \]
\[ -2x = 14 \]
\[ x = \frac{14}{-2} \]
\[ x = -7 \]
Ответ: x = -7