Here's the question you clicked on:
syhna
a machine of 75 percent efficiency is used to lift a load of 103N through a height if 4.8m. How much energy is wasted?
didn't I answer this just now? did it got deleted? work done= change in potential energy=mgh=103(4.8)J
As a first step, ignore the efficiency. How much enery is necessary to lift 103 N for 4.8 m? Once you got that number, figure out how much energy is needed by the engine (using the efficiency) and how much energy is wasted.