Assign
x to nickel (.05)
2x to the dime (.10)
5x to the quarter (.25)
x + 2x + 5x = 2.40
8x = 2.40
Divide both sides by 8 to isolate x
x = .30
Insert .30 for x in formula
.30 + (2)x(.30) + (5)x(.30) = 2.40
.30 + .60 + 1.50 = 2.40
2.40 = 2.40
Answer =
6 nickels. 6 dimes. 6 quarters