An empty rectangular tank has a capacity of 168 ℓ and a height of 20 cm. At 6 a.m., Tap V is turned on to fill the tank at a rate of 6 ℓ per minute for 15 minutes. After 14 minutes, Tap W is turned on to drain water from the tank at a rate of 3 ℓ per minute for 8 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 
3 ℓ = 3000 cm³ 
168 ℓ = 168000 cm³

Volume of water flowed in from Tap V
= 15 x 6000
= 90000 cm³

Volume of water from drained from Tap W
= 8 x 3000
= 24000 cm³

Volume of water left in the tank
= 90000 - 24000
= 66000 cm³

Base area of the tank
= 168000 ÷ 20
= 8400 cm² 

Height of water left in the tank
= 66000 ÷ 8400
≈ 7.9 cm

Answer(s): 7.9 cm