Question

18 is 45% of what ?

Answer 1

`40`

Explanation:

`18/40` will give you `0.45`, which is equal to `45%`.

How to solve it:

1. `" "18 = 0.45x`

2. `" "18/0.45 = x`

3. `" "40 = x`

Answer 2

`40`

Explanation:

The proportion I like to use with these types of problems goes like:

`"percent"/100 = "part"/"whole"`

Part/whole can also be written as "is/of"

So in this case:

• The part (is) is `18`
• The whole (of) is unknown to us - let's say `x`
• The percent (%) is `45`

Now:

`45/100 = 18/x`

We can cross multiply to get:

`45x = 1800`

`x = 40`

Hope this helps!

Answer 3

`18` is `45%` of `40`.

Explanation:

Let `x` represent the unknown number.

`45%=45/100=0.45`

`0.45x=18`

Divide both sides by `0.45`.

`x=18/(0.45)`

`x=40`

Check.

`0.45(40)=18`

`18` is `45%` of `40`.