6x – 7 = 14 – x

The first thing you need to do is collect all the 'like terms' on the same side of the equation. Start with the 'x' terms and remember to reverse the signs as you cross them over to the other side. 

7x - 7 =14

Now do the same with the numbers. 

7x = 21

Since there is an invisible multiplication sign between the '7' and the 'x', divide both sides by 7 to find the value of x. 

x = 3