Question

A water tank is leaking at a rate of 6 gallons per hour.

Answer 1

The tank is leaking at the rate of 6 gallons per hour.

If you do nothing but sit there and watch it all afternoon,
here's what you'll see:

First hour . . . . 6 gallons leaks out
Second hour . another 6 gallons leaks out
Third hour . . . another 6 gallons leaks out

Total gone after 3 hours: (6 + 6 + 6) = 18 gallons . 

Answer 2

The answer is D because 6 times 3 is 18