If a 25.5 kg child climbs 2 steps of 20 cm each, the work performed is

M = 25.5 kg, the mass of the child

h = 2*20 = 40 cm = 0.4 m

g = 9.8 m/s², acceleration due to gravity.

The work done is equal to the increase in PE (potential energy).

Therefore the work done is

W = (mg) * h

= (25.5*9.8 N) * (0.4 m)

= 99.96 J

Answer: 99.96 J