Answer:
Step-by-step explanation:
I made a table with a pretend number of years of teaching by picking a somewhat random number to start
"Clark has less seniority than Cornwall but more than Prendergast:"  I picked 3 for Clark 4 for Cornwall, and 2 for Prendergast, to start.
"Prendergast has more than Brown but less than Alexander:"  I see I'm running out of easy numbers here.  "Prendergast has more than Brown" means give Brown 1 year but this new teacher, Alexander needs a number between Clark and Prendergast.  To make room, I increased Clark and Cornwall by 1 and finished the remainder in the "Final Years" column:
<u>Teacher </u>     <u>Years</u>     <u> Final Years</u>
Clark         3               4
Cornwall         4               5
Prendergast                  2    
Brown                          1
Alexander                  3
The highest seniority teacher, Cornwall, is smart and refuses the job.  That leaves Clark, at number 2 seniority, to become the new supervisor.