The height of water in a rectangular tank is given by h(w), where w is the volume of water (in liters) that has been removed from the tank. The height of the water decreases 10mm per liter removed.
a. From the time when 7 L have been removed to the time when 15 L have been removed, the accumulated change in the height of the water is
b. If the initial height of the water is 600mm, then the height of the water after w liters have been removed is