SOLUTION: a car used 14 gal. of gas an traveled a total distance of 550 mi. the car's fuel efficiency is 40 mi./gal on the highway and 35 mi/gal in the city. how many gal of gasoline were us

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Question 153398: a car used 14 gal. of gas an traveled a total distance of 550 mi. the car's fuel efficiency is 40 mi./gal on the highway and 35 mi/gal in the city. how many gal of gasoline were used on the highway?
write linear equation and solve
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
a car used 14 gal. of gas and traveled a total distance of 550 mi. the car's fuel efficiency is 40 mi./gal on the highway and 35 mi/gal in the city. how many gal of gasoline were used on the highway?
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Let h be distance on highway ; Let c be distance in city.
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EQUATIONS:
distance equation: h + c = 550
gas use equation : (h/40 + c/35) = 14
Simplifying the 2nd equation:
7h + 8c = 3920
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EQUATIONS:
h + c = 550
7h+8c = 3920
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Modify:
8h + 8c = 4400
7h + 8c = 3920
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h = 480 miles (distance traveled on the highway)
480/40 = 12 gallons (# of gallons of gas used in highway travel)
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Cheers,
Stan H.