\[\frac{3}{8}x + 15 = \frac{1}{6}x + 10\]
\[\frac{9}{24}x - \frac{4}{24}x = 10 - 15\]
\[\frac{5}{24}x = - 5\]
\[x = - \frac{5 \cdot 24}{5} = - 24.\]