Xiaowei and Xiaoli go to the bookstore to buy books. They see a set of four books of scientific exploration. Xiaowei's money is not enough, and it's 14.5 yuan short. Xiaoli's money is not enough

Xiaowei and Xiaoli go to the bookstore to buy books. They see a set of four books of scientific exploration. Xiaowei's money is not enough, and it's 14.5 yuan short. Xiaoli's money is not enough

Xiaowei and Xiaoli went to the bookstore to buy books, and they saw a set of four scientific exploration books. Xiaowei's money was not enough, and the difference was 14.5 yuan. Xiaoli's money was not enough, and the difference was 19.9 yuan. Later, they put the money together and bought the series. If the price of each book in the series was the same, how much was the average price of each book? Together, it was just