# 18 is what percent of 80?

Jun 5, 2017

$18$ is 22.5% of $80$.

#### Explanation:

The way I am going to solve this is through fractions.

As we should all know, x% = x/100

this means that we can make this equation:

$\frac{18}{80} = \frac{x}{100}$

We can solve this by finding out how $\frac{18}{80}$ gets to $\frac{x}{100}$

(18 xx y = x)/(80 xx y = 100

In this equation, it is important to remind you that $y$ in all parts of this equation are the same.

This means that you need to multiply $80$ to get to $100$ by the same number as you need to multiply $80$ to get to $x$. Now we can solve the equation.

First, we find out what $y$ is from simple algebra working on the denominator of the equation.

$80 \times y = 100$

We can move $80$ to the other side by dividing each side by $80$

$\frac{\cancel{80}}{\cancel{80}} \times y = \frac{100}{80}$

y = 100 ÷ 80

color(lime)(y = 1.25

Now we can input $1.25$ in for $y$.

(18 xx y = x)/(80 xx y = 100

(18 xx 1.25 = x)/(80 xx 1.25 = 100

$18 \times 1.25 = x$

Now we can use simple math to find $x$.

$18 \times 1.25 = x$

$18 \times 1.25 = 22.5$

color(blue)(x = 22.5

Now we can input $x$ for $22.5$ in the original equation.

$\frac{18}{80} = \frac{x}{100}$

$\frac{18}{80} = \frac{22.5}{100}$

$\therefore$ $18$ is 22.5% of $80$.