Problema Solution

Marissa has $3.90 in quarters and dimes. If she has 3 more quarters than dimes, how many of each coin does she have?

Answer provided by our tutors

1 dime = 10 cents

1 quarter = 25 cents


let


d = the number of dimes Marissa has

q = the number of quarters Marissa has


Marissa has $3.90 = 390 cents in quarters and dimes


25q + 10d = 390 divide both sides by 5


5q + 2d = 78


she has 3 more quarters than dimes


q = 3 + d


by solving the system of equations


5q + 2d = 78

q = 3 + d


we find


d = 9 dimes


q = 12 quarters


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Marissa has 9 dimes and 12 quarters.