3-81=x

Solution for 3-81=x equation:

Simplifying
3 + -81 = x

Combine like terms: 3 + -81 = -78
-78 = x

Solving
-78 = 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.
-78 + -1x = x + -1x

Combine like terms: x + -1x = 0
-78 + -1x = 0

Add '78' to each side of the equation.
-78 + 78 + -1x = 0 + 78

Combine like terms: -78 + 78 = 0
0 + -1x = 0 + 78
-1x = 0 + 78

Combine like terms: 0 + 78 = 78
-1x = 78

Divide each side by '-1'.
x = -78

Simplifying
x = -78