An empty rectangular container has a capacity of 174 ℓ and a height of 20 cm. At 9 a.m., Tap L is turned on to fill the container at a rate of 8 ℓ per minute for 18 minutes. After 11 minutes, Tap M is turned on to drain water from the container at a rate of 9 ℓ per minute for 8 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 
8 ℓ = 8000 cm³ 
9 ℓ = 9000 cm³ 
174 ℓ = 174000 cm³

Volume of water flowed in from Tap L
= 18 x 8000
= 144000 cm³

Volume of water from drained from Tap M
= 8 x 9000
= 72000 cm³

Volume of water left in the container
= 144000 - 72000
= 72000 cm³

Base area of the container
= 174000 ÷ 20
= 8700 cm² 

Height of water left in the container
= 72000 ÷ 8700
≈ 8.3 cm

Answer(s): 8.3 cm