To add the fractions \( \frac{3}{8} \) and \( \frac{3}{4} \), you need a common denominator. The least common denominator (LCD) of 8 and 4 is 8.
Convert \( \frac{3}{4} \) to an equivalent fraction with a denominator of 8:
\[ \frac{3}{4} = \frac{3 \times 2}{4 \times 2} = \frac{6}{8} \]
Now, you can add the two fractions:
\[ \frac{3}{8} + \frac{6}{8} = \frac{3 + 6}{8} = \frac{9}{8} \]
So, \( \frac{3}{8} + \frac{3}{4} = \frac{9}{8} \), or \( 1 \frac{1}{8} \) as a mixed number.