6+3(4-3a)=90

Solution for 6+3(4-3a)=90 equation:

Simplifying
6 + 3(4 + -3a) = 90
6 + (4 * 3 + -3a * 3) = 90
6 + (12 + -9a) = 90

Combine like terms: 6 + 12 = 18
18 + -9a = 90

Solving
18 + -9a = 90

Solving for variable 'a'.

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

Add '-18' to each side of the equation.
18 + -18 + -9a = 90 + -18

Combine like terms: 18 + -18 = 0
0 + -9a = 90 + -18
-9a = 90 + -18

Combine like terms: 90 + -18 = 72
-9a = 72

Divide each side by '-9'.
a = -8

Simplifying
a = -8