An empty rectangular tank has a capacity of 139 ℓ and a height of 100 cm. At 7 a.m., Tap D is turned on to fill the tank at a rate of 7 ℓ per minute for 16 minutes. After 2 minutes, Tap E is turned on to drain water from the tank at a rate of 5 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 
7 ℓ = 7000 cm³ 
5 ℓ = 5000 cm³ 
139 ℓ = 139000 cm³

Volume of water flowed in from Tap D
= 16 x 7000
= 112000 cm³

Volume of water from drained from Tap E
= 8 x 5000
= 40000 cm³

Volume of water left in the tank
= 112000 - 40000
= 72000 cm³

Base area of the tank
= 139000 ÷ 100
= 1390 cm² 

Height of water left in the tank
= 72000 ÷ 1390
≈ 51.8 cm

Answer(s): 51.8 cm