(-3a+6)-(3a+9)=

Solution for (-3a+6)-(3a+9)= equation:

Simplifying
(-3a + 6) + -1(3a + 9) = 0

Reorder the terms:
(6 + -3a) + -1(3a + 9) = 0

Remove parenthesis around (6 + -3a)
6 + -3a + -1(3a + 9) = 0

Reorder the terms:
6 + -3a + -1(9 + 3a) = 0
6 + -3a + (9 * -1 + 3a * -1) = 0
6 + -3a + (-9 + -3a) = 0

Reorder the terms:
6 + -9 + -3a + -3a = 0

Combine like terms: 6 + -9 = -3
-3 + -3a + -3a = 0

Combine like terms: -3a + -3a = -6a
-3 + -6a = 0

Solving
-3 + -6a = 0

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 + -6a = 0 + 3

Combine like terms: -3 + 3 = 0
0 + -6a = 0 + 3
-6a = 0 + 3

Combine like terms: 0 + 3 = 3
-6a = 3

Divide each side by '-6'.
a = -0.5

Simplifying
a = -0.5