An empty rectangular tank has a capacity of 79 ℓ and a height of 200 cm. At 6 a.m., Tap M is turned on to fill the tank at a rate of 9 ℓ per minute for 20 minutes. After 6 minutes, Tap N is turned on to drain water from the tank at a rate of 5 ℓ per minute for 28 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 
5 ℓ = 5000 cm³ 
79 ℓ = 79000 cm³

Volume of water flowed in from Tap M
= 20 x 9000
= 180000 cm³

Volume of water from drained from Tap N
= 28 x 5000
= 140000 cm³

Volume of water left in the tank
= 180000 - 140000
= 40000 cm³

Base area of the tank
= 79000 ÷ 200
= 395 cm² 

Height of water left in the tank
= 40000 ÷ 395
≈ 101.3 cm

Answer(s): 101.3 cm