# How to solve proportion?

## -b/2 = -6/4

Apr 5, 2018

$b = 3$

#### Explanation:

$\frac{- b}{2} = \frac{- 6}{4}$
By cross-multiplication:
$- 4 b = - 12$
$b = - \frac{12}{-} 4$
$b = 3$

Apr 5, 2018

See below.

#### Explanation:

To solve a proportion, we use the process known as "cross-multiplication ".

This process looks something like this:

We are given the proportion:

$\frac{\textcolor{b l u e}{- b}}{\textcolor{red}{2}} = \frac{\textcolor{g r e e n}{- 6}}{\textcolor{p u r p \le}{4}}$

Using the process of cross-multiplication, we should have:

$\frac{\textcolor{b l u e}{- b}}{\textcolor{red}{2}} = \frac{\textcolor{g r e e n}{- 6}}{\textcolor{p u r p \le}{4}}$

$\implies \textcolor{p u r p \le}{4} \left(\textcolor{b l u e}{- b}\right) = \textcolor{red}{2} \left(\textcolor{g r e e n}{- 6}\right)$

$\implies - 4 b = - 12$

From here, we only need to solve for $b$:

$- 4 b = - 12$

$\implies \frac{- 4 b}{\textcolor{red}{- 4}} = - \frac{12}{\textcolor{red}{- 4}}$

$\implies b = 3$