# How would I work out a problem like this?? (ratios and proportions)

## I'm a little rusty on ratios and proportions because I haven't done them in a while. My problem is $\frac{x - 1}{8} = \frac{x + 2}{10}$

Jul 10, 2018

$x = 13$

#### Explanation:

By cross multiplication we get
$10 \left(x - 1\right) = 8 \left(x + 2\right)$
dividing by $2$

$5 \left(x - 1\right) = 4 \left(x + 2\right)$
expanding

$5 x - 5 = 4 x + 8$
adding $5$ and subtracting $4 x$

$x = 13$