4. A rectangular dam has a rectangular base 1400 me- ters long and b = 180 meters wide. Its cross section is shown below. The height is h = 150 meters and the top is w = 40 meters wide. By slicing horizon- tally, set up a definite integral giving the volume of material used to build this dam. Write your inte- grand in terms h, the distance of the slice from the top of the dam. Be sure to include the differential. W