3+12-9=y

Solution for 3+12-9=y equation:

Simplifying
3 + 12 + -9 = y

Combine like terms: 3 + 12 = 15
15 + -9 = y

Combine like terms: 15 + -9 = 6
6 = y

Solving
6 = y

Solving for variable 'y'.

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

Add '-1y' to each side of the equation.
6 + -1y = y + -1y

Combine like terms: y + -1y = 0
6 + -1y = 0

Add '-6' to each side of the equation.
6 + -6 + -1y = 0 + -6

Combine like terms: 6 + -6 = 0
0 + -1y = 0 + -6
-1y = 0 + -6

Combine like terms: 0 + -6 = -6
-1y = -6

Divide each side by '-1'.
y = 6

Simplifying
y = 6