Working together, Alex and Millie can file all the papers in the file cabinets in 4 hours. It would have taken Alex 6 hours to do the job alone. What is the missing value in the table that represents the part of the papers that Alex would file if Alex and Millie worked together? A table showing Rate in part per hour, Time in hours, and Part of Papers Filed. The first row shows Alex, and has blank, blank, and question mark. The second row shows Millies, r, 4 and 4 r.

4r
StartFraction 4 Over 6 EndFraction.
6r
StartFraction 6 Over 4 EndFraction.