Isabella had a week to read a book for school assignment. She read an average of 36 pages per day for the first three days and an average of 44 pages per day for the next three days. She then finished the book by reading 10 pages on the last day. How many pages were in the book?

Isabella read a total of 36 x 3 = <<36*3=108>>108 pages for the first three days.

She read a total of 44 x 3 = <<44*3=132>>132 pages for the next three days.
Therefore, she read a total of 108 + 132 + 10 = <<108+132+10=250>>250 pages for the week.
Thus, there were 250 pages in the book. Answer: \boxed{250}.