For a better understanding of the answer please find the diagram in the attachment.
As can be clearly seen from the diagram that the distance, "d" (shown in dark blue) of 100 feet which is covered on the sloped/inclined road is actually making an angle of only 30 degrees with the force of 200 pounds which is being applied on the road. That angle of 30 degrees is what matters.
So, the force, F=200 pounds
distance, d=100 feet
And the angle between the force, F and the distance, d is:
Therefore, as per formula, the work, W, done will be:
This, when applied to the question we have will give us:
