To simplify \( \frac{3}{7}x + \frac{2}{7}x \), we can combine the like terms:
\[ \frac{3}{7}x + \frac{2}{7}x = \left(\frac{3 + 2}{7}\right)x = \frac{5}{7}x \]
So the simplified expression is:
\[ \frac{5}{7}x \]
Therefore, the correct response is:
Start Fraction 5 over 7 End Fraction x.