When faced with a question like this, the aim is to work out the value of "x". What this question basically means is "what number can we multiply by 2 and add 1 onto it to get 11. There a few methods to tackle this question, one of which involves taking away the numbers from one side and adding them to the other whilst leaving the x on the other side, followed my dividing through by the coefficient of x, giving x = 5.Another method is to construct a number line and mark the number 11 on it, then from 0 we can draw one jump to 1, then we know the rest of the space between 1 and 11 represent the value of 2x. So 2x = 10 and from this we can work out that x = 5 (This method makes much more sense when drawn out).