3(a+2)+a=90

Solution for 3(a+2)+a=90 equation:

Simplifying
3(a + 2) + a = 90

Reorder the terms:
3(2 + a) + a = 90
(2 * 3 + a * 3) + a = 90
(6 + 3a) + a = 90

Combine like terms: 3a + a = 4a
6 + 4a = 90

Solving
6 + 4a = 90

Solving for variable 'a'.

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

Add '-6' to each side of the equation.
6 + -6 + 4a = 90 + -6

Combine like terms: 6 + -6 = 0
0 + 4a = 90 + -6
4a = 90 + -6

Combine like terms: 90 + -6 = 84
4a = 84

Divide each side by '4'.
a = 21

Simplifying
a = 21