9+3(a-1)=30

Solution for 9+3(a-1)=30 equation:

Simplifying
9 + 3(a + -1) = 30

Reorder the terms:
9 + 3(-1 + a) = 30
9 + (-1 * 3 + a * 3) = 30
9 + (-3 + 3a) = 30

Combine like terms: 9 + -3 = 6
6 + 3a = 30

Solving
6 + 3a = 30

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 + 3a = 30 + -6

Combine like terms: 6 + -6 = 0
0 + 3a = 30 + -6
3a = 30 + -6

Combine like terms: 30 + -6 = 24
3a = 24

Divide each side by '3'.
a = 8

Simplifying
a = 8