# How do you solve 5(3x + 12) = -15?

Apr 28, 2018

$x = - 5$

#### Explanation:

$\text{divide both sides by } 5$

$\frac{\cancel{5}}{\cancel{5}} \left(3 x + 12\right) = \frac{- 15}{5}$

$\Rightarrow 3 x + 12 = - 3$

$\text{subtract 12 from both sides}$

$3 x \cancel{+ 12} \cancel{- 12} = - 3 - 12$

$\Rightarrow 3 x = - 15$

$\text{divide both sides by 3}$

$\frac{\cancel{3} x}{\cancel{3}} = \frac{- 15}{3}$

$\Rightarrow x = - 5$

$\textcolor{b l u e}{\text{As a check}}$

Substitute this value into the left side of the equation and if equal to the right side then it is the solution.

$5 \left(- 15 + 12\right) = 5 \times - 3 = - 15 = \text{ right side}$

$\Rightarrow x = - 5 \text{ is the solution}$