The answer is 11 because since you are trying to find the value of x you would have to isolate x. The way you would is bring 6 to the other side with 28 because what ever you do to one side you have to do the other side. So, 28 - 6 = 22.
2x = 22
Now you can divide 2 by 2 and 22 by 2 so x is alone. 22/2 = 11 and that is the value of x.