ok i need help on this other question

Question

please

A 56.0 kg skier is at the top of a slope. At the initial point A, the skier is 14.0 m vertically above the final point B.

(a) find the difference in gravitational potential energy associated with the skier at the points A and B if the zero lever for gravitational potential energy is at ppoint B. answer in units of J

ok so this is what i did

PE = mgh
56kg(9.81)(14.0m)
=7691.04J

(B) find the difference in potential energy if the zero level is at point A. in units of J

(C) find the difference in potential energy if the zero level is midway down the slope at a height of 7.00m . in units of J

ok in parts B and C what does it mean to be at zero level?
i don't get it

Answer 1

zero level is where you measure from.
In b), the PE has decreased again (It went down).
In c), it still goes down,

PE= mg (H2-H1) Where H2 is the height from H2 to zero, and H1 is the height from zero.