SOLUTION: Starting with a full tank of gas, if you use 9 gallons of gasoline, your car can go another 315 miles before running out of fuel. After using 14 gallons, your car can go another 24

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Question 1082652: Starting with a full tank of gas, if you use 9 gallons of gasoline, your car can go another 315 miles before running out of fuel. After using 14 gallons, your car can go another 240 miles.
What is your average fuel efficiency? miles per gallon
How many miles could you drive in this car on a full tank of gas? miles
Found 2 solutions by josmiceli, josgarithmetic:
Answer by josmiceli(19441) (Show Source):
You can put this solution on YOUR website!
Let = the number of gallons in a full tank
The fuel efficiency is:

and, also:

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The fuel efficiency doesn't change, so:

Multiply both sides by

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The fuel efficiency is:

15 miles/gallon
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The miles you could drive on a full tank:

450 miles
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check:

15 miles/gallon
OK

Answer by josgarithmetic(39616) (Show Source):
You can put this solution on YOUR website!
9 gallons to 14 gallons, difference of 5 gallons.

"go another 315 miles", and then "go another 240 miles", made a difference of 75 miles.

Traveled 75 miles and used 5 gallons of gasoline:
Fuel efficiency, .

DISTANCE FOR FULL TANK
9 gallons fuel, and the remaining distance of 315 miles;

-----for a full tank