How do you solve simultaneous equations?

A simultaneous equation is when we have 2 equations which both have X and Y in them. The best way to solve these equations is to rearrange one of them to make either X or Y the subject, and then substitute it into the other equation. This gives you an equation with just one of X and Y in it which you can easily solve by expanding brackets and rearranging. This will tell you what either X or Y is equal to, which can then be substituted back into one of the starting equations to find the other term.