An empty rectangular container has a capacity of 57 ℓ and a height of 20 cm. At 7 a.m., Tap N is turned on to fill the container at a rate of 10 ℓ per minute for 16 minutes. After 9 minutes, Tap P is turned on to drain water from the container at a rate of 3 ℓ per minute for 13 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 
10 ℓ = 10000 cm³ 
3 ℓ = 3000 cm³ 
57 ℓ = 57000 cm³

Volume of water flowed in from Tap N
= 16 x 10000
= 160000 cm³

Volume of water from drained from Tap P
= 13 x 3000
= 39000 cm³

Volume of water left in the container
= 160000 - 39000
= 121000 cm³

Base area of the container
= 57000 ÷ 20
= 2850 cm² 

Height of water left in the container
= 121000 ÷ 2850
≈ 42.5 cm

Answer(s): 42.5 cm