Answer:
1/3 of they tank can be filled in 20 min. and in 20 min, the pipe fills up 500 liters.
Explanation:
So 20 minutes is 1/3 of an hour so it makes sense to say that 1/3 of the tank would be filled up in 1/3 of an hour. Next if the pipe can fill up the tank in 1 hr min then we would have to just divide it by 3 to find how much it can do in 20 min. So 1500/3 = 500 liters in 20 min. (Hope this helps)