To find out what percent of 500 is 20, you can use the formula:
\[ \text{Percent} = \left( \frac{\text{part}}{\text{whole}} \right) \times 100 \]
In this case, the part is 20 and the whole is 500. Therefore, the calculation is:
\[ \text{Percent} = \left( \frac{20}{500} \right) \times 100 \]
Calculating this gives:
\[ \text{Percent} = \left( \frac{20}{500} \right) \times 100 = 0.04 \times 100 = 4 \]
So, 20 is 4% of 500. The answer is 4.