The figure, not drawn to scale, shows an empty tank measuring 20 cm by 25 cm by 15 cm. Water flows from Tap C at a rate of 500 mℓ per minute and from Tap D at a rate of 230 mℓ per minute. Tower E and Tower F have a base area of 20 cm² and 80 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 17 minutes.
Volume of the tank
= 20 x 25 x 15
= 7500 cm³ 

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

Volume of water flow in 17 minutes
= 17 x 570
= 9690 cm³ 

Volume of water in the 2 towers
= 9690 - 7500
= 2190 cm³ 

Total combined base areas of 2 towers
= 20 + 80
= 100 cm² 

Height of water in 2 towers
= 2190 ÷ 100
= 21.9 cm

Total height of water
= 21.9 + 15
= 36.9 cm

Answer(s): 36.9 cm