Percentage of a percentage

What is `50%` of `40%`?

You need to reword this slightly and say:

What is `50%` of `40` ?

Now we can work this out.

Multiply both sides by `x` to get `x` on its own.

  `(cancelxtimes40)/cancelx=(100timesx)/50`

`40=(100x)/50`

`40=2x` 

Divide both sides by `2` to get `x` on its own

   `40/2=(cancel2x)/cancel2`

`x=40/2`

Answer: `x=20%`