Answer:
The answer to your question is:
1st Diego
2nd Diego and Elena ( both 15 days)
Step-by-step explanation:
Data
Lin      54 pages        270-page book          3 days
Diego  100 pages        320 page               4 days
Elena  160 pages         480 page               5 days
Process
Lin
             54 pages    -------------------  3 days
            270 page     -----------------    x
             x = (270 x 3) / 54
             x = 15 days
Diego
            100 pages     -----------------  4 days
            320          --------------------  x
            x = (320 x 4) / 100
            x = 12.8 days
Elena  Â
            160 pages -------------------  5 days
            480 pages --------------------  x
            x = (480 x 5) / 160
            x = 15 days