Answer:
32340J
Explanation:
Given parameters
Height of skyscraper  = 45m
Height of crane  = 10m
Mass of worker = 60kg
g = 9.81m
Unknown:
Gravitational potential energy  = ?
Solution:
The gravitational potential energy of a body is the energy due to the position of the body.
It is expressed as:
   G.P.E  = mgh
m is the mass
g is the acceleration due to gravity
h is the height = 45 + 10 Â = 55m
G.P.E Â = 60 x 9.8 x 55 Â = 32340J