Question

15. Suppose a car gas tank holds 21 gallons of gas. On a trip it uses 2/3 of a tank of gas on a trip. Then it uses 1/3 of what is left in the tank. How many gallons of gas are left in the tank? *

Answer 1

Answer:

4 2/3 gallons of gas

Step-by-step explanation:

Step 1

Suppose a car gas tank holds 21 gallons of gas.

On a trip it uses 2/3 of a tank of gas on a trip.

= 2/3 × 21 gallons of gas

= 14 gallons of gas

Step 2

Then it uses 1/3 of what is left in the tank.

The number of gallons of gas left =

21 gallons of gas - 14 gallons of gas

= 7 gallons of gas

Hence, this is calculated as:

1/3 × 7 gallons of gas

= 2 1/3 gallons of gas

Step 3

How many gallons of gas are left in the tank?

This is calculated as:

7 gallons of gas - 2 1/3 gallons of gas

= 7/1 - 7/3

Lowest common denominator =

= 21 - 7/3

= 14/3

= 4 2/3 gallons of gas is left

Therefore, 4 2/3 gallons of gas is left.