An empty rectangular tank has a capacity of 108 ℓ and a height of 80 cm. At 9 a.m., Tap J is turned on to fill the tank at a rate of 5 ℓ per minute for 18 minutes. After 9 minutes, Tap K is turned on to drain water from the tank at a rate of 7 ℓ per minute for 10 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 
5 ℓ = 5000 cm³ 
7 ℓ = 7000 cm³ 
108 ℓ = 108000 cm³

Volume of water flowed in from Tap J
= 18 x 5000
= 90000 cm³

Volume of water from drained from Tap K
= 10 x 7000
= 70000 cm³

Volume of water left in the tank
= 90000 - 70000
= 20000 cm³

Base area of the tank
= 108000 ÷ 80
= 1350 cm² 

Height of water left in the tank
= 20000 ÷ 1350
≈ 14.8 cm

Answer(s): 14.8 cm