Question

Darnell's car used 8 gallons of gasoline to travel 340 mils. After a mechanic worked on the car, it used 7 gallons of gasoline to travel 350 miles. If the price of gasoline was about 4 dollars per gallon, how much less, to the nearest cent per mile, did it cost to run the car after the mechanic worked on it

Answer 1

It costs $0.01 / mile less than before the mechanic worked on it.

Explanation:

Cost to run the car before the mechanic worked on it:

`4 * 8 = 32 dollars\\32 * 1/340 = 0.09 dollars/mile`

Cost to run the car after the mechanic worked on it:

`4 * 7 = 28 dollars28 * 1/350 = 0.08 dollars/mile`

The difference between both cases is:

`0.09 - 0.08 = 0.01 dollars/mile`