SOLUTION: A family has two cars. The first car has a fuel efficiency of 35 miles per gallon, the second car has a fuel efficiency of 40 miles per gallon. The two cars drove a combined tota

Question 948418: A family has two cars. The first car has a fuel efficiency of 35 miles per gallon, the second car has a fuel efficiency of 40 miles per gallon. The two cars drove a combined total of 2600 miles, in which equaled out to 70 gallons of gas used in one week. How many gallons of gas were used by each vehicle?

Found 2 solutions by josgarithmetic, macston:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
That is the same form of fuel efficiency problem as asked in this example which has been solved:

http://www.algebra.com/algebra/homework/coordinate/word/Linear_Equations_And_Systems_Word_Problems.faq.question.948009.html

Study that problem and solution. If you understand it, then you should be able to solve yours.
Answer by macston(5194) (Show Source): You can put this solution on YOUR website!
A=miles on car with 35 mpg; B=miles on car with 40 mpg
A+B=2600 Solve for A
A=2600-B
Substitute for A
Multiply each side by 35 mpg
Multiply each side by 8.
20800-8B+7B=19600 Subtract 19600 from each side.
1200 miles-B=0 Add B to each side.
1200 miles=B The 40 mpg car drove 1200 miles.
A+B=2600 miles
A+1200 miles=2600 miles Subtract 1200 miles from each side.
A=1400 miles The 35 mpg car drove 1400 miles
ANSWER 1: The 35 mpg car used 40 gallons.
ANSWER 2: The 40 mpg car used 30 gallons.

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