Leo has 12 coins, all of which are quarters and nickels. In all, they're worth $2.00. How many of each kind of coin does Leo have?

Answer 1

Let N = number of nickels

Q = number of quarters

Then .25Q + .05N = 2 Multiply by 4, Q + .2N = 8

and Q + N = 12 Keep the same Q + N = 12

Subtracting top equation from the bottom, we get .8N = 4 or N = 5

and Q = 7

Check .25(7) + .05(5) = 2 OK!