\( 3\frac{8}{9} = \frac{3 \cdot 9 + 8}{9} = \frac{27 + 8}{9} = \frac{35}{9} \)
\( 5\frac{1}{12} = \frac{5 \cdot 12 + 1}{12} = \frac{60 + 1}{12} = \frac{61}{12} \)
\( x - \frac{35}{9} = \frac{61}{12} \)
\( x = \frac{61}{12} + \frac{35}{9} \)
\( \frac{61}{12} = \frac{61 \cdot 3}{12 \cdot 3} = \frac{183}{36} \)
\( \frac{35}{9} = \frac{35 \cdot 4}{9 \cdot 4} = \frac{140}{36} \)
\( x = \frac{183}{36} + \frac{140}{36} = \frac{183 + 140}{36} = \frac{323}{36} \)
\( \frac{323}{36} = 8 \frac{35}{36} \) (так как \( 323 = 8 \times 36 + 35 \))
Ответ: \( x = 8\frac{35}{36} \).