The figure, not drawn to scale, shows an empty tank measuring 20 cm by 15 cm by 25 cm. Water flows from Tap S at a rate of 400 mℓ per minute and from Tap T at a rate of 180 mℓ per minute. Tower U and Tower V have a base area of 30 cm² and 70 cm² respectively. Water is drained out of the container at a rate of 120 mℓ per minute. Find the height of the water level after 17 minutes.
Volume of the tank
= 20 x 15 x 25
= 7500 cm³ 

Volume of water flow per minute
= 400 + 180 - 120
= 460 cm³/min

Volume of water flow in 17 minutes
= 17 x 460
= 7820 cm³ 

Volume of water in the 2 towers
= 7820 - 7500
= 320 cm³ 

Total combined base areas of 2 towers
= 30 + 70
= 100 cm² 

Height of water in 2 towers
= 320 ÷ 100
= 3.2 cm

Total height of water
= 3.2 + 25
= 28.2 cm

Answer(s): 28.2 cm