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2014 AMC 12B Problem 1

Problem 1 of 25EasierAlgebra

Leah has 1313 coins, all of which are pennies and nickels. If she had one more nickel than she has now, then she would have the same number of pennies and nickels. In cents, how much are Leah’s coins worth?

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Solution

Let nn be the number of nickels, so Leah has 13n13-n pennies. One more nickel would give her n+1n+1 nickels, and this equals the number of pennies: n+1=13n. n+1 = 13-n. Solving gives n=6,n=6, so there are 66 nickels and 77 pennies. The total value is 65+7=376\cdot5 + 7 = 37 cents. Thus, the correct answer is C.

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Concepts: linear equation · money

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