Literal equations can be treated just like regular algebra, but what can be hard about them is the fact that they contain no real values, instead variables. Let's look at the one you've given me, u=x-k. Let's use the properties we know about equations and flip the equation around a little bit, making it into -k+x=u. Next, we can simply add k to both sides, getting us x=u+k. Hope this helps.
