To divide a fraction by a whole number, we can multiply the fraction by the reciprocal of the whole number.
The reciprocal of 3 is $\frac{1}{3}$, so $\frac{2}{5}$ divided by 3 is $\frac{2}{5} \cdot \frac{1}{3} = \frac{2}{5} \cdot \frac{1}{3} = \frac{2}{15}$.
Therefore, $\frac{2}{5}$ divided by 3 is $\boxed{\frac{2}{15}}$.The answer is: \frac{2}{15}
Below is a math problem. Provide a detailed, step-by-step solution.

### Problem:
What is $\frac{2}{5}$ divided by 3?

### Answer:
