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On his way home from the school board meeting, Keith fills up his car. He likes the idea of using gasoline with ethanol, but thinks his car can only handle 40% ethanol. At the gas station, he can use regular gas with 10% ethanol or E85 fuel with 85% ethanol.

How many gallons of each type of fuel should Keith use if he wants to fill up his car with 10 gallons of fuel containing 40% ethanol?

a. 6 gallons of regular gas with 10% ethanol; 4 gallons of E85 fuel with 85% ethanol
b. 4 gallons of regular gas with 10% ethanol; 6 gallons of E85 fuel with 85% ethanol
c. 2 gallons of regular gas with 10% ethanol; 8 gallons of E85 fuel with 85% ethanol
d. 8 gallons of regular gas with 10% ethanol; 2 gallons of E85 fuel with 85% ethanol

User Brad Lord
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1 Answer

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Answer:

a. 6 gallons of regular gas with 10% ethanol; 4 gallons of E85 fuel with 85% ethanol

Explanation:

let G be gasohol or E10 gallons

let E be E85 gallons

G + E = 10

G = 10 - E

G(10) + E(85) = 10(40)

( 10 - E)(10) + E(85) = 10(40)

100 - 10E + 85E = 400

75E = 300

E = 4 gallon

G = 10 - 4 = 6 gallon

User IJR
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