# How do you solve 10/3=(r+6)/(r+9)?

Feb 27, 2017

The solution is $r = - \frac{72}{7}$ or $- 10 \frac{2}{7}$.

#### Explanation:

Solve:

$\frac{10}{3} = \frac{r + 6}{r + 9}$

Cross multiply.

$10 \left(r + 9\right) = 3 \left(r + 6\right)$

Expand.

$10 r + 90 = 3 r + 18$

Subtract $3 r$ from both sides.

$7 r + 90 = 18$

Subtract $90$ from both sides.

$7 r = - 72$

Divide both sides by $7$.

$r = - \frac{72}{7}$

As a mixed fraction:

$r = - 10 \frac{2}{7}$