The gas tank on Juanita's car holds 20 gallons of gas. The fuel gauge of the car shows that the gas tank is 3/4 full. How many gallons of gas are in the gas tank?

15 gallons

Step-by-step explanation:

So the easiest way to solve this one is basic reasoning. It's easy to find 3/4 of a number if you know what 1/4 is.

20/4 = 5, or 1/4 of 20 = 5

3/4 is 3 times as much as 1/4, so 5 (3) = 15

Or, you can solve using a proportion

3 x

_ = _

4 20

(those are fractions)

Cross multipy

3 (20) = 4x

60 = 4x

Divide both sides by 4 to isolate the variable

15 = x

The final way to solve this is by converting the decimal to a fraction. 3/4 = 0.75

20 x 0.75 = 15