Given,

Mass of man = 70 kg

Weight carried = 10 kg

Height above ground h = 100 m

Work done =???

Total mass at top of tower = 70 + 10

M = 80 kg

For a body of mass m to raise to height h above earth,

Work done = potential energy stored

= M × g × h

Let g = 10 ms^-2

So, work done will be = 80×10×100

= 80,000 J

= 80 KJ