Write a system of equations to describe the situation below, solve using substitution, and fill in the blanks.
Last Wednesday, two friends met up after school to read the book they were both assigned in Literature class. Denise can read 1 page per minute, and she had already read 57 pages. Ed, who has a reading speed of 3 pages per minute, had read 41 pages. Eventually they had read the same number of pages. How many pages had each of them read? How long did that take?