So,
GPE (graviational potential energy) = mass x g x height
GPE is depends on where zero height is defined. In this situation, we define h = 0 as the initial height.
[tex]GPE = 75 \ kg*9.8 \ \frac{m}{s^2}*25 \ m[/tex]
[tex]GPE = 18,375 \frac{kg*m^2}{s^2}[/tex]
[tex]GPE = 18,375 \ joules(J) \ or \ 18.375 \ kilojoules(kJ)[/tex]
The builder has gained 18.375 kJ of PE.