# How do you solve 3a + 12+ ( - 3a ) = 5a + 7+ ( - 3a )?

Apr 15, 2018

color(brown)(a = 5/2

#### Explanation:

Carryout the operations as per the order above while solving an equation.

$3 a + 12 + \left(- 3 a\right) = 5 a + 7 + \left(- 3 a\right)$

$3 a + 12 - 3 a = 5 a + 7 - 3 a , \text{ removing brackets}$

$3 a - 3 a + 12 = 5 a - 3 a + 7 , \text{ rearranging like terms together}$

$\cancel{3 a} - \cancel{3 a} + 12 = {\cancel{5 a - 3 a}}^{\textcolor{red}{2 a}} + 7$

$12 = 2 a + 7$

$2 a = 12 - 7 , \text{ separating constants and variables}$

$2 a = 5 \text{ or } a = \frac{5}{2}$