I also think we should use the power of mice. Let the teacher give you administrative communication, which may prevent you from accepting excessive punishment. This is the first step. The second step should be for you to go to the teacher and admit your mistake to the classmate who borrowed the book but lost it. If it is really lost by a classmate, the classmate should compensate at least half of the fine. The third step is to change this system. If borrowing books must be borne by the borrower, then the borrower should not be borne by the designated person. Because it is relatively unfair to make a behavioral borrower responsible for the results of the actual borrower's behavior.

I hope it helps you!