Jenny filled 2/3 of a rectangular tank with water. The tank is 60 cm long, 20 cm wide, and 40 cm high.

(a) Jenny then poured out 20 liters of water. The remaining water was used to fill up 450 ml mugs to the brim. What is the most number of mugs Jenny could fill?

(b) After filling up the number of mugs in (a), how much water was left in the tank?