12-3(a+1)=3+a

Solution for 12-3(a+1)=3+a equation:

Simplifying
12 + -3(a + 1) = 3 + a

Reorder the terms:
12 + -3(1 + a) = 3 + a
12 + (1 * -3 + a * -3) = 3 + a
12 + (-3 + -3a) = 3 + a

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

Solving
9 + -3a = 3 + a

Solving for variable 'a'.

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

Add '-1a' to each side of the equation.
9 + -3a + -1a = 3 + a + -1a

Combine like terms: -3a + -1a = -4a
9 + -4a = 3 + a + -1a

Combine like terms: a + -1a = 0
9 + -4a = 3 + 0
9 + -4a = 3

Add '-9' to each side of the equation.
9 + -9 + -4a = 3 + -9

Combine like terms: 9 + -9 = 0
0 + -4a = 3 + -9
-4a = 3 + -9

Combine like terms: 3 + -9 = -6
-4a = -6

Divide each side by '-4'.
a = 1.5

Simplifying
a = 1.5