It is an expression which can not be factored, hence it is difficult to detail much other than factoring out '5'.  A closer look at the process can be reviewed by clicking on a particular solutions step or adjusting the number of solution steps by clicking on the 'Options' tab and choose 'a lot of steps'.  Generally, it is best to start off with 'a few steps' and only increase the number of solution steps when the additional detail is clarifying rather than confusing.