Neil has a total of twelve $5 and $10 bills in his wallet. He has 5 times as many $10 bills as $5 dollar bills. How many of each does he have?

Answer 1

Let x = $5 bills
5x = $10 bills

x + 5x = 12
6x = 12
x = 2

Answer 2

y=x-6
y=2x