This situation is a very useful english conversation in both ways whether you want to borrow somone's money or to refuse someone when they borrow you money.
Example 1
Friend : Do you have some extra money?
You : How much do you want?
Friend : Ten dollars
You : Here you are.
Friend : Thank you. I will pay you back soon.
Example 2
Friend : Can I borrow some money? I'm so broke.
You : How much do you need?
Friend : 50 bucks
You : Here you go.
Friend : Thanks a lot
Example 3
Friend : Could you lend me some money?
You : I'm afraid I can't.
Friend : That's alright.