First, combine all the like terms. The terms we have are 2x and 4x. Are they similar? Do they have the same letter? Yes, so they can be combined as stated in the question. It tells us we have to add so we add 2x to 4x. To do this imagine x is an apple, so 2x is 2 apples and 4x is 4 apples. If we add the two what do, we get? 6 apples. So 2x + 4x is 6x. Now we have 6x = 12. Now we want to have just 1x on the left-hand side. So how do we make 6x into 1x without adding or subtracting. We divide by 6. This gives us 1x. Now remember what you do to one side must be done to the other and since we divided one side by 6, we must divide the other by six. So, 12 divided by 6 is 2. This gives us 1x = 2 or x = 2.