Another way you can solve this problem...
Start by getting the parenthesis on a side all by itself (dividing both sides of the equation by 6).
This leaves you with: (1+9x) = -20/6
Now you can drop the parenthesis, getting: 1+9x = -20/6
The next step is to isolate the variable "x". This will take two steps. The first step involves subtracting 1 from both sides of the equation.
Subtracting 1 from both sides gets: 9x = -20/6 - 1
Convert 1 to 6/6 (because these numbers are both equal you are allowed to do this): 9x = -20/6 - 6/6
Solving the subtracting of fractions gives you: 9x = -26/6
The second step to solve for the variable "x" is to divide both sides of the equation by the multiplier attached to the x (in other words, the number 9). Remember diving by 9 is the same as multiplying by the fraction 1/9.
Dividing both sides by 9, get you: x = -26/6 * 1/9
Solving the multiplication of the fractions gets you your answer. I'll leave that to you :) Hope this helped!