Question

A family has two cars. The first car has a fuel efficiency of 15 miles per gallon of gas and the second has a fuel efficiency of 30 miles per gallon of gas. During

one particular week, the two cars went a combined total of 1425 miles, for a total gas consumption of 60 gallons. How many gallons were consumed by each of
the two cars that week?
.
First car: gallons

Second car: gallons

Answer 1

15x+30(60-x)=1425

15x+1800-30x=1425

-15x=-375

x=25

—————————————————————
35+y=60


60-25


Y=35



Car 1 consumes 25 gallons of gas.
Car 2 consumes 35 gallons of gas.

Answer 2

Let x = gallons consumed by car 1

Let y = gallons consumed by car 2

We set up our equations:

35x+40y = 1850 eq1

x+y = 50 eq2

Substituting eq 2 into eq 1,

35x+40(50-x) = 1850

35x+2000-40x = 1850

-5x+2000 = 1850

-5x = -150

x = 30

Substitute value of x into eq 2.

x+y = 50

30+y = 50

y = 20

Car 1 consumes 30 gallons of gas.

Car 2 consumes 20 gallons of gas

Explanation: