SOLUTION: In a family there are two cars. The sum of the average miles per gallon obtained by the two cars in a particular week is 35 . The first car has consumed 30 gallons during that week

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Question 317832: In a family there are two cars. The sum of the average miles per gallon obtained by the two cars in a particular week is 35 . The first car has consumed 30 gallons during that week, and the second has consumed 40 gallons, for a total of 1200 miles driven by the two cars combined. What was the average gas mileage obtained by each of the two cars in that week?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
For each car, (miles driven)/(gallons consumed) = miles/gallon
Let a = average miles driven by 1st car
Let b = average miles driven by 2nd car
given:
(1) a+%2B+b+=+1200 miles
a%2F30+%2B+b%2F40+=+35
Multiply both sides by 120
(2) 4a+%2B+3b+=+4200
Multiply both sides of (1) by 3
and subtract (1) from (2)
(2) 4a+%2B+3b+=+4200
(1) -3a+-+3b+=+-3600
a+=+600
b+=+1200+-+600
b+=+600
The ave gas milage for a is 600%2F30+=+20 mi/gal
The ave gas milage for b is 600%2F40+=+15 mi/gal