Gerald had 20 toy cars. He donated 1/4 of his toy cars to an orphanage. How many toy cars does Gerald have left?
Step-by-step reasoning:
15
Gerald gave away 20 x 1 / 4 = 5 of his toy cars.

Therefore, he is left with 20 - 5 = 15 toy cars.

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So, the final answer is 15