An empty rectangular tank has a capacity of 189 ℓ and a height of 126 cm. At 7 a.m., Tap L is turned on to fill the tank at a rate of 5 ℓ per minute for 17 minutes. After 10 minutes, Tap M is turned on to drain water from the tank at a rate of 3 ℓ per minute for 13 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 
3 ℓ = 3000 cm³ 
189 ℓ = 189000 cm³

Volume of water flowed in from Tap L
= 17 x 5000
= 85000 cm³

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

Volume of water left in the tank
= 85000 - 39000
= 46000 cm³

Base area of the tank
= 189000 ÷ 126
= 1500 cm² 

Height of water left in the tank
= 46000 ÷ 1500
≈ 30.7 cm

Answer(s): 30.7 cm