An empty rectangular container has a capacity of 164 ℓ and a height of 20 cm. At 9 a.m., Tap B is turned on to fill the container at a rate of 4 ℓ per minute for 18 minutes. After 14 minutes, Tap C is turned on to drain water from the container at a rate of 7 ℓ per minute for 5 minutes. What is the height of the water level in the container in the end? Give the answer in 1 decimal place.
1 ℓ = 1000 cm³ 
4 ℓ = 4000 cm³ 
7 ℓ = 7000 cm³ 
164 ℓ = 164000 cm³

Volume of water flowed in from Tap B
= 18 x 4000
= 72000 cm³

Volume of water from drained from Tap C
= 5 x 7000
= 35000 cm³

Volume of water left in the container
= 72000 - 35000
= 37000 cm³

Base area of the container
= 164000 ÷ 20
= 8200 cm² 

Height of water left in the container
= 37000 ÷ 8200
≈ 4.5 cm

Answer(s): 4.5 cm