Answer:
ok, you didnt make a proper sentence but i might have a answer for u. if you have $20, spent it on the mailing package for $3.67, you have $16.33 left. then you want to buy as much stamps as possible. you divide $16.33 by $.37, you get 44.1 . so in that case, you can get 41 stamps.
if anything, feel free to ask me anything.