I guess I am not completely understanding this problem, but the question is you are painting a monument, a rectangular prism. The height and width is given to me (width = 30) (height = 40) and the question asks for the amount of paint needed to pain the sides of the monument, in square feet. So do I just solve for the area of the rectangular prism? The question does not provide any more details than that.
With the given information, you can calculate the area of the 2 sides (left and right), but nothing else.
This results in 2(30)(40), or sq feet of space to be painted.