An empty rectangular tank has a capacity of 21 ℓ and a height of 30 cm. At 6 a.m., Tap J is turned on to fill the tank at a rate of 8 ℓ per minute for 15 minutes. After 5 minutes, Tap K is turned on to drain water from the tank at a rate of 2 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 
8 ℓ = 8000 cm³ 
2 ℓ = 2000 cm³ 
21 ℓ = 21000 cm³

Volume of water flowed in from Tap J
= 15 x 8000
= 120000 cm³

Volume of water from drained from Tap K
= 8 x 2000
= 16000 cm³

Volume of water left in the tank
= 120000 - 16000
= 104000 cm³

Base area of the tank
= 21000 ÷ 30
= 700 cm² 

Height of water left in the tank
= 104000 ÷ 700
≈ 148.6 cm

Answer(s): 148.6 cm