a tank of 18 cubic meters capacity is filled with water fully in 1hour 30 minutes the filling rate in litres per minute is
1 hour 30 min is 90 min; therefore,
18 m^3/90 min = 0.2 m^3/min.
Now convert 0.2 m^3 to L
1 m^3 = 1000 L
Post your work if you get stuck.