Answer:
Since it says graph I will assume there are graphs that go along with this?
If this is an open ended question you can find out how much water is left after (t) minutes by doing this equasion:
1,000/50=20
(t) being minutes so the answer to (t) would be 20 minutes
(y) being water would be 1,000gal
Final Answer: 1,000gal in 20 min
