10. Xiao Wang and Xiao Li both brought some money to buy the book "Harry - Potter". When they arrived at the bookstore, they found that the money Xiao Wang brought was 6 yuan short of buying 2 copies, and the money Xiao Li brought was 31 yuan short of buying 2 copies. However, the money the two brought together was just enough to buy 3 copies. The price of each copy of "Harry Potter" is ( ) yuan.
【Answer】 37
【Analysis】The two people together are short of 37 yuan to buy 4 books, and their combined money is just enough to buy 3 books, which means one book costs 37 yuan.
【Lecture Note Comparison】Profit and loss application problem, Short-term Class Lecture 1