"A load of mass 80kg fell dwn from d floor of a lorry whch is 1.2m high.calculate wrk dne by gravity on d land "
If you can write the question in normal plain english you are more likely to get a correct answer. You should also get in the habit of correctly spacing number and units as this will then come automatically when you type or write.
Assuming that you need to calcualte the work done when a mass of 80 kg falls 1.2 m under gravity (assume that g = 9.8 m s^-2).
Force on the mass is
mass x acceleration =
1.8 kg x 9.8 m s^-2 = 17.64 N
work done is
force x distance
= 17.64 N x 1.2 m = 21.168 N m
or 21 N m to 2 sig figs (assuming that the mass 80 kg is to 2 sig figs).