An empty rectangular tank has a capacity of 132 ℓ and a height of 80 cm. At 7 a.m., Tap R is turned on to fill the tank at a rate of 6 ℓ per minute for 20 minutes. After 15 minutes, Tap S is turned on to drain water from the tank at a rate of 6 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 
6 ℓ = 6000 cm³ 
6 ℓ = 6000 cm³ 
132 ℓ = 132000 cm³

Volume of water flowed in from Tap R
= 20 x 6000
= 120000 cm³

Volume of water from drained from Tap S
= 13 x 6000
= 78000 cm³

Volume of water left in the tank
= 120000 - 78000
= 42000 cm³

Base area of the tank
= 132000 ÷ 80
= 1650 cm² 

Height of water left in the tank
= 42000 ÷ 1650
≈ 25.5 cm

Answer(s): 25.5 cm