Answer:Pipe 1 is emptying the pool at 600,000/200 = 3000 liters per minute.
The second pipe empties the pool at 600,000/120 =5000 litres per minute. With both pipes the pool will be emptied at 8000 litres per minute. It will therefore take 600,000/8000 = 75 minutes to empty the pool of water when both pipes are draining together.
Explanation: