When Nayeli and Filémon have the same number of pages left, they will each have approximately 20 pages left.
First find how many pages each manuscript has remaining at a rate of 11 pages per hour:
75 pages - 11 pages/hour * t = 0 pages
40 pages - 4 pages/hour * t = 0 pages
Solve for t to find the number of hours it takes them both to have no pages left:
75 pages - 11 pages/hour * t = 40 pages - 4 pages/hour * t
35 pages = 7 pages/hour * t
t = 5 hours
Then multiply the number of hours by the slower line editor's rate to find how many pages remain:
5 hours * 4 pages/hour = 20 pages
Therefore, when Nayeli and Filémon have the same number of pages left, they will each have approximately 20 pages left.