Answer:
13n+20
Step-by-step explanation:
If 20 is the flat rate, then you dont put x to it. X is how many books you are going to get and 13 is how much you have to pay for each book. If that makes sense.
Brainliest?
The expression will be the price per book times the amount of books, n, plus the shipping rate.
13n + 20
<em>I hope this helps :)</em>
the third graph........................................