12=a+b

Solution for 12=a+b equation:

Simplifying
12 = a + b

Solving
12 = a + b

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.
12 + -1a = a + -1a + b

Combine like terms: a + -1a = 0
12 + -1a = 0 + b
12 + -1a = b

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

Combine like terms: 12 + -12 = 0
0 + -1a = -12 + b
-1a = -12 + b

Divide each side by '-1'.
a = 12 + -1b

Simplifying
a = 12 + -1b