# 45 is what percent of 90?

Jan 19, 2017

$45$ is 50% of $90$.

#### Explanation:

$\frac{45}{90} = \frac{x}{100}$, where $x$ is the percentage.

$90 x = 4500 \implies x = 50$.

Equations of the form $\frac{a}{b} = \frac{c}{d}$ can be transformed to $a d = b c$.

In general, for any $a , b$ with $b \ne 0$, from the equation $\frac{a}{b} = \frac{x}{100}$,

$x$ shows you what percentage $a$ is, of $b$.