Carlotta does 2000 j of work on a machine. The machine does 500 J of work what is the efficiency of this machine

Efficiency of a machine = (useful output energy) / (total input energy)

Efficiency = (500 J output work) / (Carlotta's 2,000 J input work)

Efficiency = (500 J) / (2,000 J)

Efficiency = 0.25

Efficiency = 25%