Linear Functions: Is it Filling Up or Draining Out?

I. There are four tanks of water. The amount of water in gallons, A, in
Tank A is given by the function A=200+8t, where t is in minutes. The
amount of water in gallons, B, in Tank B starts at 400 gallons and is
decreasing at 5 gallons per minute. These functions work when t0
and t80.
a) Which tank started out with more water?

b) Write an equation representing the relationship between B and t.

c) One tank is filling up. The other is draining out. Which is which? How
can you tell?

d) The amount of water in gallons, C, in Tank C is given by the function
C=800−7t. Is it filling up or draining out? Can you tell just by looking at
the equation?