Margie's car can go 32 miles on a gallon of gas, and gas currently costs 4 per gallon. how many miles can margie drive on $20 worth of gas?

$20 means Margie can buy 5 gallons . . . (i.e. $20 / $4 per gallon = 5 gallons)

we know she can go 32 miles on every gallon, so we just multiply by the 5 gallons she just bought with her $20, and find out she can make it 160 miles (i.e. 32×5 = 160)

answer is 160 miles