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2012 AMC 10A Problem 1

Problem 1 of 25EasierArithmetic

Cagney can frost a cupcake every 2020 seconds and Lacey can frost a cupcake every 3030 seconds. Working together, how many cupcakes can they frost in 55 minutes?

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Solution

Cagney can make 60÷20=360 \div 20 = 3 cupcakes per minute, and Lacey can make 60÷30=2.60 \div 30 = 2. In 55 minutes, they can make 5(2+3)=5⋅5=25. 5(2 + 3) = 5 \cdot 5 = 25. Thus, D is the correct answer.
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