Problema Solution
On his way home from the school board meeting, Kevin fills up his car. He likes the idea of using gasoline with ethanol, but thinks his car can only handle 20% ethanol. At the gas station, he can use regular gas with 10% ethanol or E85 fuel with 85% ethanol.
How many gallons of E85 fuel should Kevin use if he wants to fill up his car with 10 gallons of fuel containing 20% ethanol?
Answer provided by our tutors
Let 'x' represent the amount of 10% ethanol Kevin uses, then '10-x' represents the amount of 85% ethanol he uses in order to obtain a 20% ethanol mixture.
0.1x+0.85(10-x)=0.2x
8 2/3
10-8(2/3) = 1(1/3)
So Kevin fills in 8 2/3 10% ethanol and adds 1 1/3 85% ethanol.