Take an equation, for instance. If a regular X is on the right side, then solve everything on the left side (Y) to get the answer. You need to solve the question the same way. Think about it, could 2y-3=x be solved like this? 2y-3=2y-3? It could, and it would be as stupid as using the question as the answer.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram