To find out what percentage of the pizza Lily ate, we first need to calculate the total parts in the ratio, which is 9 + 11 = 20.
Then, we find out how many parts Lily ate, which is 9 out of 20 parts.
To convert this into a percentage, we use the formula:
Percentage = Number of parts eaten / Total parts × 100
Plugging in the values:
Percentage = 9 / 20 × 100
Therefore, Lily ate 45% of the pizza.
