Find current and power factor in circuit
If you know the input power and the output power then the difference is the power lost.... in the feed wires.

Do you know how to calculate the power dissipated in a resistor based on what current is flowing through it? If yes, then you reverse this formula to uncover what current must be flowing to dissipate the power lost in the feed wire. When you have done this you'll find that your prof is right and he also made the assumption that the feed wire between generator and load was purely resistive.

Let's see if you can figure this out by your comments. PF is 0.72 by the way so let's see if you can figure this out too.