If 9% of a number is 18, what is the number?

Feb 6, 2017

The number is $200$

Explanation:

Let the number be $x$

$9$ percent of the number means
$\textcolor{w h i t e}{\text{XXX}} \frac{9}{100} \times x$

So if $18$ is $9$ percent of the number:
$\textcolor{w h i t e}{\text{XXXXXXXXXX")18=color(white)("XXXX}} \frac{9}{100} \times x$

$\textcolor{w h i t e}{\text{XXX}} \rightarrow \frac{100}{9} \times 18 = \frac{100}{9} \times \frac{9}{100} \times x$

$\textcolor{w h i t e}{\text{XXX}} \rightarrow \frac{100}{\cancel{9}} \times {\cancel{18}}^{2} = \frac{\cancel{100}}{\cancel{9}} \times \frac{\cancel{9}}{\cancel{100}} \times x$

$\textcolor{w h i t e}{\text{XXX")rarrcolor(white)("XXXXX")200 = color(white)("XXXXXXXXX}} x$