Question

A 13.5-gallon gasoline tank is 4/5 full. How many gallons will it take to fill the tank?

Answer 1

divide 13.5 by 5
=2.7
then multiply 2.7 by 4
=10.8
so the tank has 10.8 gallons when 4/5 full
it takes 2.7 more gallons to fill the tank.
a simpler way would be to just divide by 5 and that would get the answer, but if you needed to know how many gallons were already in the tank, the way i showed up there would work.

Answer 2

we know that

if the gasoline tank is
`(4)/(5)` full

then

`(5)/(5) -(4)/(5) =(1)/(5)`

So

Multiply
`13.5\ gal` by
`(1)/(5)` to know the number of gallons required to fill it

`13.5*(1)/(5) =(13.5)/(5) \\ \\ =2.7\ gallons`

therefore

the answer is

`2.7\ gallons`