An empty rectangular tank has a capacity of 146 ℓ and a height of 80 cm. At 6 a.m., Tap R is turned on to fill the tank at a rate of 9 ℓ per minute for 18 minutes. After 11 minutes, Tap S is turned on to drain water from the tank at a rate of 8 ℓ per minute for 17 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 
9 ℓ = 9000 cm³ 
8 ℓ = 8000 cm³ 
146 ℓ = 146000 cm³

Volume of water flowed in from Tap R
= 18 x 9000
= 162000 cm³

Volume of water from drained from Tap S
= 17 x 8000
= 136000 cm³

Volume of water left in the tank
= 162000 - 136000
= 26000 cm³

Base area of the tank
= 146000 ÷ 80
= 1825 cm² 

Height of water left in the tank
= 26000 ÷ 1825
≈ 14.2 cm

Answer(s): 14.2 cm