\( \frac{x}{4} - 12 = 13 - \frac{x}{3} \)
\( \frac{x}{4} + \frac{x}{3} = 13 + 12 \)
\( \frac{3x}{12} + \frac{4x}{12} = 25 \)
\( \frac{7x}{12} = 25 \)
\( 7x = 25 × 12 \)
\( 7x = 300 \)
\( x = \frac{300}{7} \)
Ответ: x = 300/7.