whatever you do to the left hand side of the equation, you must also do it to the right hand side. for example, in qn 2, the first step is to add 8 to the equation so that -8+8=0. when you do that, you must add 8 on the right hand side also, so that 4+8=12. so the equation becomes (n/6)=12. so when you add, subtract, multiply or divide on one side of the equation, you must do the same to the other side of the equation.