Question

Five is three more than a number n. I don't understand this at all!

Answer 1

N+3=5
n+3-3=5-3 (subtract 3 on both sides)
n=2
to check you substitute n with 2 and you get 2+3=5 (5=5)

Answer 2

So what they are telling you is that 5 is three higher than the variable n.
So n = 5-3 
so n is 2.