Question 121857
Well you really dont need the parentheses because there are no multiplication attached to the () so lets remove them for simplicity's sake

3x + 6 + 2x - 11 = 90

Step 1:  Combine like terms (for those not familiar in like terms, a like term is where the letters are the same (x is different from y,) and the same exponent ( and x is different from x^2,)
(3x + 2x = 5x)
(6 - 11 = -5)
so your left with this:
5x - 5 = 90

Step 2: Solve for variable
when solving for one variable you have to move everything else away.  First I move the -5 by adding 5 to both sides
5x = 95
then you have to divide by 5 because how do you get rid of something that is being multiplied 
x = (I know you can divide)