3(a+2)-9=12

Solution for 3(a+2)-9=12 equation:

Simplifying
3(a + 2) + -9 = 12

Reorder the terms:
3(2 + a) + -9 = 12
(2 * 3 + a * 3) + -9 = 12
(6 + 3a) + -9 = 12

Reorder the terms:
6 + -9 + 3a = 12

Combine like terms: 6 + -9 = -3
-3 + 3a = 12

Solving
-3 + 3a = 12

Solving for variable 'a'.

Move all terms containing a to the left, all other terms to the right.

Add '3' to each side of the equation.
-3 + 3 + 3a = 12 + 3

Combine like terms: -3 + 3 = 0
0 + 3a = 12 + 3
3a = 12 + 3

Combine like terms: 12 + 3 = 15
3a = 15

Divide each side by '3'.
a = 5

Simplifying
a = 5