Answer:
Sally ate 40% of the pizza and there was 60% of the pizza leftover.
Explanation:
A percentage is a rate, number, or amount in each hundred.
There were 10 slices of pizza, she ate 4.
4/10 = 40/100 multiplied by 10, which would let us find the percentage.
Therefore, Sally ate 40% of the pizza and left 60% back.
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