A rectangle with base b and height h has an isosceles triangle
that has base b and height h on the top of the rectangle as
shown below. The b is decreasing at a rate of 3 cm per minute,
while h is increasing at a rate of 5 cm per minute. What is the
rate of change of the area when the base is 73 and the height is
37? Is the area increasing or decreasing at the same time and how
do you know which it is?