I have enough money to buy the book with.为什么加with`

问题描述:

I have enough money to buy the book with.为什么加with`

with 用错了。不过一楼的说法是对的。
但是用to了就不必再用with。

因为我觉得i buy the book with the money.我觉得不加也行吧

I want buy the book with the money.
这样可以理解了吗?