#### Answer

a) 0 J
b) $49,000J$
c) $-60,000 J$

#### Work Step by Step

We know the following equation:
$U = mgh$
Knowing that each floor is 3.5 meters tall, we find:
a) 0 J; Since she defines her office as ground level, potential energy here is 0 Joules.
b) She is 26 floors above her office, so she is $ 26 \times 3.5 = 91 m$ above her office. Thus:
$U= 55 \times 9.81 \times 91 = 49,000J$
c) She is 32 floors below her office, so she is $ 32 \times 3.5 = 112 m$ below her office.
Thus:
$U= 55 \times 9.81 \times --12 = -60,000 J$