The figure, not drawn to scale, shows an empty container measuring 50 cm by 15 cm by 15 cm. Water flows from Tap E at a rate of 500 mℓ per minute and from Tap F at a rate of 240 mℓ per minute. Tower G and Tower H have a base area of 30 cm² and 70 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 container
= 50 x 15 x 15
= 11250 cm³ 

Volume of water flow per minute
= 500 + 240 - 140
= 600 cm³/min

Volume of water flow in 19 minutes
= 19 x 600
= 11400 cm³ 

Volume of water in the 2 towers
= 11400 - 11250
= 150 cm³ 

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

Height of water in 2 towers
= 150 ÷ 100
= 1.5 cm

Total height of water
= 1.5 + 15
= 16.5 cm

Answer(s): 16.5 cm