81=3a-3a-4a

Solution for 81=3a-3a-4a equation:

Simplifying
81 = 3a + -3a + -4a

Combine like terms: 3a + -3a = 0
81 = 0 + -4a
81 = -4a

Solving
81 = -4a

Solving for variable 'a'.

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

Add '4a' to each side of the equation.
81 + 4a = -4a + 4a

Combine like terms: -4a + 4a = 0
81 + 4a = 0

Add '-81' to each side of the equation.
81 + -81 + 4a = 0 + -81

Combine like terms: 81 + -81 = 0
0 + 4a = 0 + -81
4a = 0 + -81

Combine like terms: 0 + -81 = -81
4a = -81

Divide each side by '4'.
a = -20.25

Simplifying
a = -20.25