car averages 20 miles per gallon of gas in city driving and 30 miles per gallon in highway driving. At these rates, how many gallons of gas will the car use on a 300-mile trip if 4/5 of the trip is highway driving and the rest is city driving?

Answer 1

4/5 of 300 = 240
so, the gas used is
60/20 + 240/30

Answer 2

The gas used is 11

Answer 3

4/5 of 300
= 4/5 x 300
= 240
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Meaning, the gas used is...
60/20 + 240/30
= 3 + 8
= 11
∴ 11 gallons of gas were used.