An empty rectangular tank has a capacity of 146 ℓ and a height of 50 cm. At 10 a.m., Tap G is turned on to fill the tank at a rate of 8 ℓ per minute for 17 minutes. After 4 minutes, Tap H is turned on to drain water from the tank at a rate of 9 ℓ per minute for 10 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 
8 ℓ = 8000 cm³ 
9 ℓ = 9000 cm³ 
146 ℓ = 146000 cm³

Volume of water flowed in from Tap G
= 17 x 8000
= 136000 cm³

Volume of water from drained from Tap H
= 10 x 9000
= 90000 cm³

Volume of water left in the tank
= 136000 - 90000
= 46000 cm³

Base area of the tank
= 146000 ÷ 50
= 2920 cm² 

Height of water left in the tank
= 46000 ÷ 2920
≈ 15.8 cm

Answer(s): 15.8 cm