What is the answer plz help me plz nad it is non-equivalent

The head librarian at the library of congress has asked her assistant for an interval estimate of the mean number of books checked out each day. the assistant provides the following interval estimate: from 740 to 920 books per day. what is an efficient, unbiased point estimate of the number of books checked out each day at the library of congress?

You have 138.72 in your saving account u take out 45.23 and 18.00 you deposit 75.85 into your account

Can someone explain to me how to do