A diver begins at sea level and dives down 200 feet. He ascends at a steady rate of 12 1/3 feet per minute for 4.5 minutes. Which of the following numerical expressions represents the final depth of the diver?

Suppose the depth of the diver is d at time time t, rate is given by r=12 1/3 ft / min. The equation representing the depth of the diver at time t will be:

f (t) = 200 - (12 1/3) t

Therefore the depth of the diver after t=4.5 min will be:

f (4.5) = 200 - (12 1/3) * 4.5

f (4.5) = 200-55.5

f (4.5) = 144.5 ft

This means that after 4.5 minutes the diver will be 144.5 ft deep.