A machine moves a 600-kg object 6 meters. If the amount of work put into the machine is 4500 joules, what is the efficiency of the machine?
You need to calculate the work output of the machine. The efficiency is simply the ratio of work output over work input.
Work = Force x distance.
However, there is not enough information provided to calculate the force. If the object is being lifted then the force is 9.81 x 600. If the object is being dragged across a horizontal surface then the force is dependent on a coefficient of friction. There are many other possibilities, the object could be dragged up a hill or through a viscous fluid.