The figure, not drawn to scale, shows an empty tank measuring 20 cm by 15 cm by 20 cm. Water flows from Tap R at a rate of 500 mℓ per minute and from Tap S at a rate of 230 mℓ per minute. Tower T and Tower U have a base area of 40 cm² and 60 cm² respectively. Water is drained out of the container at a rate of 160 mℓ per minute. Find the height of the water level after 19 minutes.
Volume of the tank
= 20 x 15 x 20
= 6000 cm³ 

Volume of water flow per minute
= 500 + 230 - 160
= 570 cm³/min

Volume of water flow in 19 minutes
= 19 x 570
= 10830 cm³ 

Volume of water in the 2 towers
= 10830 - 6000
= 4830 cm³ 

Total combined base areas of 2 towers
= 40 + 60
= 100 cm² 

Height of water in 2 towers
= 4830 ÷ 100
= 48.3 cm

Total height of water
= 48.3 + 20
= 68.3 cm

Answer(s): 68.3 cm