To find what percent 9 is of 20, you can use the formula:
\[ \text{Percentage} = \left( \frac{\text{part}}{\text{whole}} \right) \times 100 \]
In this case, the part is 9 and the whole is 20.
\[ \text{Percentage} = \left( \frac{9}{20} \right) \times 100 \]
Now perform the calculation:
\[ \text{Percentage} = 0.45 \times 100 = 45 \]
So, 9 is 45% of 20.