Actually I believe that Coach Link is incorrect in saying that he can only make 91 teams of 1 or 1 team of 91.
To find the number of teams he can make, we have to find the whole number that can divide 91 and give also a whole number answer. In this case, I found it to be 7.
91 / 7 = 13
So this means that Coach Link can also make 7 teams of 13 or 13 teams of 7.