
Mahendra K. answered 06/10/15
Tutor
New to Wyzant
Experienced Engineer , Mathematics and Hindi Tutor
Let us assume the car which runs 40 miles per gallon consumed X gallons that week.
Therefore the other car , which runs 15 miles per gallon , consumed ( 75- X) gallons that week.
The first car has fuel efficiency of 40 miles per gallon and therefore this car did 40*X miles that week
The other car which has fuel efficiency of 15 miles per gallon did 15*(75- X) miles
It is given that two cars went combined 2125 miles
Therefore [ 40*X + 15*(75- X) ] = 2125
40 X + 1125 - 15 X =2125
40 X - 15 X = 2125-1125
25 X = 1000
X =1000/25
X = 40
The car which has fuel efficiency of 40 miles per gallon consumed 40 gallons
The other car which has fuel efficiency of 15 miles per gallon consumed = 75-40
= 35 gallons