An empty rectangular tank has a capacity of 28 ℓ and a height of 25 cm. At 9 a.m., Tap W is turned on to fill the tank at a rate of 3 ℓ per minute for 20 minutes. After 2 minutes, Tap X is turned on to drain water from the tank at a rate of 9 ℓ per minute for 5 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 
3 ℓ = 3000 cm³ 
9 ℓ = 9000 cm³ 
28 ℓ = 28000 cm³

Volume of water flowed in from Tap W
= 20 x 3000
= 60000 cm³

Volume of water from drained from Tap X
= 5 x 9000
= 45000 cm³

Volume of water left in the tank
= 60000 - 45000
= 15000 cm³

Base area of the tank
= 28000 ÷ 25
= 1120 cm² 

Height of water left in the tank
= 15000 ÷ 1120
≈ 13.4 cm

Answer(s): 13.4 cm