An empty rectangular tank has a capacity of 77 ℓ and a height of 56 cm. At 6 a.m., Tap J is turned on to fill the tank at a rate of 5 ℓ per minute for 16 minutes. After 6 minutes, Tap K is turned on to drain water from the tank at a rate of 4 ℓ per minute for 15 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 
4 ℓ = 4000 cm³ 
77 ℓ = 77000 cm³

Volume of water flowed in from Tap J
= 16 x 5000
= 80000 cm³

Volume of water from drained from Tap K
= 15 x 4000
= 60000 cm³

Volume of water left in the tank
= 80000 - 60000
= 20000 cm³

Base area of the tank
= 77000 ÷ 56
= 1375 cm² 

Height of water left in the tank
= 20000 ÷ 1375
≈ 14.5 cm

Answer(s): 14.5 cm