Answer:
Alejandro.
Carly.
Explanation:
If we express this as a relation we could called t the time in minutes and f(t) the total number of pages. So, after t = 1 min, Alejandro read 1 page, and Carly read 2 pages. When Alejandro finishes 28 pages, the time passed is 28 min, when Carly finishes 12 pages, the times passed is 6 min.
So, we can express each speed of reading like a ratio:
Alejandro:

Carly:

Also, we could define a function for each of them.
Alejandros' function:

Carly's function:

Therefore, the relations are:
Alejandro.
Carly.