Explain how you could show five less than a number using an expression

Pretty simple! What I like to do is show it circle the action words that tell us what the operations are. 

we can circle the words less and a number. (We know that less means to subtract) 

Now we need to know what to do with the number part of the problem. 

We can just represent that using X. 

Now, we are saying 5 less than a number. Which is x-5 as your final expression.