The figure, not drawn to scale, shows an empty tank measuring 20 cm by 15 cm by 15 cm. Water flows from Tap Y at a rate of 200 mℓ per minute and from Tap Z at a rate of 230 mℓ per minute. Tower A and Tower B have a base area of 60 cm² and 20 cm² respectively. Water is drained out of the container at a rate of 150 mℓ per minute. Find the height of the water level after 19 minutes.
Volume of the tank
= 20 x 15 x 15
= 4500 cm³ 

Volume of water flow per minute
= 200 + 230 - 150
= 280 cm³/min

Volume of water flow in 19 minutes
= 19 x 280
= 5320 cm³ 

Volume of water in the 2 towers
= 5320 - 4500
= 820 cm³ 

Total combined base areas of 2 towers
= 60 + 20
= 80 cm² 

Height of water in 2 towers
= 820 ÷ 80
= 10.25 cm

Total height of water
= 10.25 + 15
= 25.25 cm

Answer(s): 25.25 cm