A book with 180 pages, I read an average of 3 1 page in the first five days. On the fifth day, start reading from page 125. According to the relevant information of the query, the starting page number of the fifth day is needed, and how many pages have been read in the first four days, that is, thirty-one times four equals one hundred and twenty-four, and the fifth day begins with one hundred and twenty-five pages.