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2005 AMC 12B Problem 3

Problem 3 of 25EasierAlgebra

Brianna is using part of the money she earned on her weekend job to buy several equally-priced CDs. She used one fifth of her money to buy one third of the CDs. What fraction of her money will she have left after she buys all the CDs?

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Solution

Buying all the CDs costs three times what one third of them cost, namely 315=353\cdot\dfrac15 = \dfrac35 of her money. She has 135=251 - \dfrac35 = \dfrac25 of her money left. Thus, the correct answer is C.

More practice

Concepts: fraction · ratio and proportion

Problem text and solution from the LIVE past-contest archive. See also the AoPS wiki page for community solutions.