Question

A change machine changes dollar bills into quarters and nickels. If you receive 12 coins after inserting a dollar bill, how many nickels did you receive?

Answer 1

it should be 11

Answer 2

well its not so

Answer 3

2 quarters, 10 nickels. Give me a minute to show the math.

Answer 4

25x+5y=100
x+y=12
x=12-y
Substitute back in after solving for x.
25(12-y)+5y=100
300-25y+5y=100
300-100=20y
y=10
Back into the original problem:
x=12-10
x=2