Was that picture part of the given problem or did you draw it yourself? It is not what I would get from your description- nor is it my experience with swimming pools. You have a "lowered" section on the left with slanted sides and then up to a height of 3 feet beow the top, then flat for the rest of the forty foot length. Where did you get that "6- 12- 6- 16" along the bottom (which I assume are distances). I would, rather, have drawn the side view of the swimming pool as a single trapezoid with the two parallel ends of lengths 3 and 9 feet and the "height" 40 feet. I don't know if you were given that rather strange picture or drew it yourself.