A dealer has 10,000 gallons of unleaded gasoline. He wants to add just enough ethanol to make the fuel a 10% ethanol mixture. How many gallons of ethanol should be added?
(0)(10000) + x = .10(10000+x)
times 10
10x = 10000+9
9x = 10000
x = appr. 1111.1 gallons of ethanol