To add the fractions \( \frac{1}{8} \) and \( \frac{2}{5} \), you first need to find a common denominator.
The least common multiple (LCM) of 8 and 5 is 40.
Now, convert each fraction to have the common denominator of 40:
\[ \frac{1}{8} = \frac{1 \times 5}{8 \times 5} = \frac{5}{40} \]
\[ \frac{2}{5} = \frac{2 \times 8}{5 \times 8} = \frac{16}{40} \]
Now, add the two fractions:
\[ \frac{5}{40} + \frac{16}{40} = \frac{5 + 16}{40} = \frac{21}{40} \]
So, \( \frac{1}{8} + \frac{2}{5} = \frac{21}{40} \).