[-9]-[3]=x

Solution for [-9]-[3]=x equation:

Simplifying
[-9] + -1[3] = x
-9 + -1[3] = x

Multiply -1 * 3
-9 + -3 = x

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

Solving
-12 = x

Solving for variable 'x'.

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

Add '-1x' to each side of the equation.
-12 + -1x = x + -1x

Combine like terms: x + -1x = 0
-12 + -1x = 0

Add '12' to each side of the equation.
-12 + 12 + -1x = 0 + 12

Combine like terms: -12 + 12 = 0
0 + -1x = 0 + 12
-1x = 0 + 12

Combine like terms: 0 + 12 = 12
-1x = 12

Divide each side by '-1'.
x = -12

Simplifying
x = -12