Question

A family has two cars. The first car has a fuel efficiency of 20 miles per gallon of gas and the second has a fuel efficiency of 40 miles per gallon of gas. During one particular week, the two cars went a combined total of 1700 miles, for a total gas consumption of 55 gallons. How many gallons were consumed by each of the two cars that week

Answer 1

F= first car
S = second car
F+S =55
F= 55-S
20f+40s=1700
Using substitution method add the value of F to second equation
20(55-s)+40s=1700
1100-20s+40s=1700
1100+20s=1700
20s=600
s=30
So second car consumed 30 gallons of gas; first car consumed 25 gallons