An empty rectangular tank has a capacity of 143 ℓ and a height of 55 cm. At 8 a.m., Tap L is turned on to fill the tank at a rate of 5 ℓ per minute for 20 minutes. After 5 minutes, Tap M is turned on to drain water from the tank at a rate of 2 ℓ per minute for 27 minutes. What is the height of the water level in the tank in the end? Give the answer in 1 decimal place.
1 ℓ = 1000 cm³ 
5 ℓ = 5000 cm³ 
2 ℓ = 2000 cm³ 
143 ℓ = 143000 cm³

Volume of water flowed in from Tap L
= 20 x 5000
= 100000 cm³

Volume of water from drained from Tap M
= 27 x 2000
= 54000 cm³

Volume of water left in the tank
= 100000 - 54000
= 46000 cm³

Base area of the tank
= 143000 ÷ 55
= 2600 cm² 

Height of water left in the tank
= 46000 ÷ 2600
≈ 17.7 cm

Answer(s): 17.7 cm