The sum of $\frac{1}{5}$ and $\frac{3}{5}$ is:

$\frac{1}{5} + \frac{3}{5} = \frac{1 + 3}{5} = \frac{4}{5}$

So, $\frac{1}{5} + \frac{3}{5} = \frac{4}{5}$.

Would you like more details or have any questions?

Here are some related questions for further exploration:

1. How would you add $\frac{2}{7}$ and $\frac{3}{7}$?
2. What is the result of $\frac{4}{9} + \frac{5}{9}$?
3. How do you add fractions with different denominators?
4. What is $\frac{1}{5} - \frac{3}{5}$?
5. Can you convert $\frac{4}{5}$ to a decimal?

Tip: When adding fractions, ensure the denominators are the same before adding the numerators.