A man has 14 coins in his pocket, all of which are dimes and quarters. If the total value of his change is $2.75, how many dimes and how many quarters does he have?

1 Answer
Oct 3, 2015

The man has 5 dimes and 9 quarters.

Explanation:

This can either be solved by guessing and checking, or by setting up a system of equations. If d is the number of dimes the man has and q is the number of quarters, the fact that he has 14 coins means d+q=14. The fact that he has $2.75=275 cents means that 10d+25q=275.

d+q=14\rightarrow d=14-q

Upon substitution into the second equation, we get

10*(14-q)+25q=275\rightarrow 140-10q+25q=275

\rightarrow 15q=135\rightarrow q=135/15=9.

Therefore, d=14-9=5.