2014 AMC 12B Problem 1

Below is the professionally curated solution for Problem 1 of the 2014 AMC 12B, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2014 AMC 12B solutions, or check the answer key.

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Concepts:linear equationmoney

Difficulty rating: 920

1.

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?

3333

3535

3737

3939

4141

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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