To simplify the expression \( \frac{3}{7}x + \frac{2}{7}x \), you can combine the like terms.
Since both terms have the same coefficient \( \frac{1}{7} \) and the variable \( x \):
\[ \frac{3}{7}x + \frac{2}{7}x = \left(\frac{3 + 2}{7}\right)x = \frac{5}{7}x \]
Thus, the simplified expression is:
\[ \frac{5}{7}x \]