This problem is probably easiest using the technique we used in 7.5 from class, where we let a common number be a variable.

Here try letting $y = 5$ and see if you can solve for $y$. As in class, we need to be a little careful about what values of $x$ are possible (in the domain). The graph can help for that as well, but try to understand that algebraically as well.

Hope this helps at least get started. Let us know if you have some additional questions.