Show us the pictures I don't see it
1 Kilojoule [kJ] = 737.562 149 277 27 Foot pound force [ftlbf]
It should be S since S stands for students. Giving the team with more members the upper hand. Hope this helps.
The change in potential energy of an object is given by

where
m is the mass of the object
g is the gravitational acceleration

is the increase in altitude of the object
In our problem,

is the mass of the book,

and

is the increase in altitude of the book, so its variation of potential energy is