The figure, not drawn to scale, shows an empty tank measuring 20 cm by 15 cm by 30 cm. Water flows from Tap R at a rate of 500 mℓ per minute and from Tap S at a rate of 160 mℓ per minute. Tower T and Tower U have a base area of 50 cm² and 50 cm² respectively. Water is drained out of the container at a rate of 140 mℓ per minute. Find the height of the water level after 19 minutes.
Volume of the tank
= 20 x 15 x 30
= 9000 cm³ 

Volume of water flow per minute
= 500 + 160 - 140
= 520 cm³/min

Volume of water flow in 19 minutes
= 19 x 520
= 9880 cm³ 

Volume of water in the 2 towers
= 9880 - 9000
= 880 cm³ 

Total combined base areas of 2 towers
= 50 + 50
= 100 cm² 

Height of water in 2 towers
= 880 ÷ 100
= 8.8 cm

Total height of water
= 8.8 + 30
= 38.8 cm

Answer(s): 38.8 cm