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Jason has 46 total coins with a mixture of dimes and quarters. The total value of his coins is $6.55.
How many dimes and how many quarters does Jason have?
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Let d = # of dimes and q = # of quarters Jason has.
Then you have this system of two equations in two unknowns d and q:
d + q = 46, (1)
10d + 25q = 655. (2)
From (1), express d = 46 - q and substitute it into (2). In this way, you get a single equation for q:
10*(46 - q) + 25q = 655,
460 - 10q + 25q = 655,
15q = 655 -460,
15q = 195,
q =
= 13.
Answer. Jason has 13 quarters and 46 - 13 = 33 dimes.