SOLUTION: A family has two cars. The first car has a fuel efficiency of 40 miles per gallon of gas and the second has a fuel efficiency of 15 miles per gallon of gas. During one particular w

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Question 967601: A family has two cars. The first car has a fuel efficiency of 40 miles per gallon of gas and the second has a fuel efficiency of 15 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 45 gallons. How many gallons were consumed by each of the two cars that week?
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620) (Show Source):
You can put this solution on YOUR website!
Uniform Rates for Fuel Efficiency.
RV=D relating fuel efficiency (which is a rate), volume of fuel, distance traveled.

Treat this problem description as you would for a travel uniform-rates problem.

_________________rate____________volume____________distance
car1_____________40_____________(____)_____________(_____)
car2_____________15_____________(____)_____________(_____)
Totals___________________________45________________1425

Rate is MILES per GALLON;
Volume is GALLONS
Distance is MILES.

Just assign variables for the volume of car1 and the volume of car2, different variable for EACH OF THEM.

~~I leave the rest of this to you.~~

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Here is a continuation:
n for car oNe
w for car tWo

_________________rate____________volume____________distance
car1_____________40________________n________________40n
car2_____________15________________w________________15w
Totals___________________________45________________1425

NOW, I leave the rest of the process to you.

Answer by MathTherapy(10552) (Show Source):
You can put this solution on YOUR website!

A family has two cars. The first car has a fuel efficiency of 40 miles per gallon of gas and the second has a fuel efficiency of 15 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 45 gallons. How many gallons were consumed by each of the two cars that week?

Let number of gallons used by 1st car (40 mpg), be F
Then number of gallons used by 2nd car (15 mpg) is: 45 - F
We then get: 40F + 15(45 - F) = 1,425
40F + 675 - 15F = 1,425
40F - 15F = 1,425 - 675
25F = 750
F, or number of gallons used by 1st car (40 mpg) = , or
Number of gallons used by 2nd car (15 mpg) = 45 - 30, or