To solve the equation \( x - \frac{9}{4} = -\frac{3}{8} \), follow these steps:
- Add \(\frac{9}{4}\) to both sides of the equation:
\[ x = -\frac{3}{8} + \frac{9}{4} \]
- To add these fractions, you need a common denominator. The least common multiple of 8 and 4 is 8. Convert \(\frac{9}{4}\) to have a denominator of 8:
\[ \frac{9}{4} = \frac{9 \times 2}{4 \times 2} = \frac{18}{8} \]
- Now substitute this back into the equation:
\[ x = -\frac{3}{8} + \frac{18}{8} \]
- Combine the fractions:
\[ x = \frac{18 - 3}{8} = \frac{15}{8} \]
Thus, the value of \( x \) is
\[ \boxed{\frac{15}{8}} \]