I think he's saying that it's good practice to explicitly show that you are making a series of equivalent expressions, by writing your work not as
this
this
this
this
Hows thi
but as
this
= this
= this
= this
That isn't essential, but shows the reader what you mean, and reminds you of what you are doing.
And he's saying that you could have stopped with the next to last line, because both are equally "condensed". Some teachers, though, may want answers in radical form, and may explicitly state that in a problem.