Kevin and Randy Muise have a jar containing 71 coins, all of which are either quarters or nickels. The total value of the coins in the jar is 7.75. How many of each type of coin do they have?

Answer 1

q + n = 71 ----> q = 71 - n

25q + 5n = 775 (I multiplied the equation by 100 to get rid of the pesky decimals)

25(71 - n) + n = 71

1775 - 25n + n = 71

24n = 1704

n = 71

I bet you can figure out how many quarters there are!

Answer 2

Q + N =71

.25Q + .05N = 7.75

Multiply the 2nd equation by 20: 5Q + N = 155

Subtract the 1st equation from the 2nd

4Q = 84

You finish it from here.