Question

When a number is decreased by 20% of itself, the result is 20. What is the number?

Answer 1

25

Explanation:

Since the number is reduced by 20% we have 80% left. That 80% is equal to 20. We can use cross multiplication to relate the two.

80% is equal to `80/100=8/10=4/5`
We know that 20 is 80% of something so we have `20/x`

These two should be equal so we can do the following
`4/5=20/x`

Using cross multiplication we get
`4x=100`

Solving we get
`x=25`