Functions are basically another way of expressing a way to get y or x or anything (mostly used for graphs) You will see functions like f(x)= 23y-5 (that was made up). Basically the number in the parenthesis in front of the f is what you're finding. So the equation after the equal sign is how to find whatever is being found. So in this case, finding x can be pretty easy. By the way, when graphing this you have x as the run and y as the rise.