Question 326219: In a family there are two cars. In a given week, the first car gets an average of 40 miles per gallon, and the second car gets 30 miles per gallon. The two cars combined drive a total of 2300 miles in that week, for a total gas consumption of 65 gallons. How many gallons were consumed by each of the two cars that week?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! In a family there are two cars. In a given week, the first car gets an average of 40 miles per gallon, and the second car gets 30 miles per gallon. The two cars combined drive a total of 2300 miles in that week, for a total gas consumption of 65 gallons. How many gallons were consumed by each of the two cars that week?
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Note: distance/mpg = gallons
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1st car DATA:
mpg = 40 ; distance = x miles ; gallons = x/40
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2nd car DATA:
mph 30 ; distance = 2300-x ; gallons = (2300-x)/30
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Equation:
gallons + gallons = 65
x/40 + (2300-x)/30 = 65
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Multiply thru by 120 to get:
3x + 4(2300-x) = 65*120
3x -4x + 4*2300 = 65*120
-x = -1400
x = 1400 miles
2300-x = 900 miles
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x/40 = 35 gallons (amt. used by the 1st car)
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900/30 = 30 gallons (amt. used by 2nd car)
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Cheers,
Stan H.
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