The figure, not drawn to scale, shows an empty tank measuring 20 cm by 15 cm by 15 cm. Water flows from Tap A at a rate of 400 mℓ per minute and from Tap B at a rate of 190 mℓ per minute. Tower C and Tower D have a base area of 10 cm² and 30 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 15
= 4500 cm³ 

Volume of water flow per minute
= 400 + 190 - 160
= 430 cm³/min

Volume of water flow in 19 minutes
= 19 x 430
= 8170 cm³ 

Volume of water in the 2 towers
= 8170 - 4500
= 3670 cm³ 

Total combined base areas of 2 towers
= 10 + 30
= 40 cm² 

Height of water in 2 towers
= 3670 ÷ 40
= 91.75 cm

Total height of water
= 91.75 + 15
= 106.75 cm

Answer(s): 106.75 cm