Question

Suppose you have 57 coins in a jar consisting entirely of dimes and quarters, worth a total of $10.65. How many dimes are in the jar?

Answer 1

24

Explanation:

Let d represent the number of dimes. Then (57-d) is the number of quarters, and the total value (in cents) is ...

10d +25(57 -d) = 1065

-15d +1425 = 1065 . . . . . . simplify

-15d = -360 . . . . . . . . . . subtract 1425

d = -360/-15 = 24 . . . divide by the coefficient of d

There are 24 dimes in the jar.