Question

"alan drives an average of 100 miles each week. his car can travel an average of 25 miles per gallon of gasoline. alan would like to reduce his weekly expenditure on gasoline by $5. assuming gasoline costs $4 per gallon, which equation can alan use to determine how many fewer average miles, m, he should drive each week?"

Answer 1

68.75 miles/week

Explanation:

Alan drives an average of 100 miles each week.

His car can travel an average of 25 miles per gallon of gasoline.

Gasoline consumption per week =
`(100)/(25)= 4 gallons`

Cost of 1 gallon gasoline = $4

So., cost of 4 gallons gasoline = 4*4 = $16

Now, Alan would like to reduce his weekly expenditure on gasoline by $5.

The reduced cost would be:

`16 - 5 = \text{(New average miles/week)} * (1 gal)/(25 miles) * $4/gal`

`(11*25)/(4) = \text{(New average miles/week)}`

`68.75= \text{(New average miles/week)}`

New average miles/week = 68.75 miles/week

Answer 2

First, list all the given information:
*100 miles/week
*25 miles/gallon
*$4/gallon
*weekly expenditure reduced by $5

The easiest approach to use here is the dimensional analysis. Cancel out like units if they appear both in the numerator and denominator side. Solve first the original cost. The solution is as follows:

100 miles/week * 1 gal/25 miles * $4/gal = $16/week

The reduced cost would be:
16 - 5 = (New average miles/week) * 1 gal/25 miles * $4/gal
New average miles/week = 68.75 miles/week