The amount of water in the first tank at time t will be 200-40t
The amount of water in the second at time t is
Set them equal and solve for t. You will get two solutions.
There are 2 tanks of water. The first tank holds 200 liters and will be drained by pump at a constant rate completely in 5 hours. The second tank holds 900 liters and will be drained by opening a plug on the bottom, this tank will also drain in 5 hours. The second tanks volume will decrease according to toricellis law which is V(t)=Vo(1-t/T)^2
When will the volumes of the 2 tanks be equal?