It is true that work is measured in joules but this answer is misleading. Work is defined as force x distance so 100 joules of work would be wrong. The correct answer is "3" because the distance moved and the force applied are the same regardless of whether a ramp and hand truck are used. The vertical distance of 4 feet is the same. The amount of force needed to move the 40 pound boxes is the same whether the force is applied straight up and down or on a ramp. The ramp may make the task easier for the worker to accomplish, but it does not change the amount of work to be accomplished.