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.

Guide to work out a percentage of a percentages

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: $x=20%$