你能帮我把这些钱换成零钱吗？

Could you please break the money for me?

我想把这张100元的钞票换成零钱。

I'd like to break a hundred-yuan bill.

你可以帮我把二十块换成小钞，十块换成零钱吗?

Can you give me twenty dollars in small bills, please, and ten dollars in change?