Answer:
8 minutes
Step-by-step explanation:
Since the level of the tank needs to be at two-thirds its original level, then this means that Andrew needs to drain only one-third of the fish tank. Therefore the amount of time it would take can easily be solved with this 2-step equation...
6t = 144 * .... first multiply the right side of the equation
6t = 48 ... next divide both sides by 6
t = 8
Finally, we can see that it will take Andrew 8 minutes to drain the tank to two-thirds of its original level.