An empty rectangular tank has a capacity of 86 ℓ and a height of 50 cm. At 8 a.m., Tap F is turned on to fill the tank at a rate of 4 ℓ per minute for 17 minutes. After 10 minutes, Tap G is turned on to drain water from the tank at a rate of 2 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 
4 ℓ = 4000 cm³ 
2 ℓ = 2000 cm³ 
86 ℓ = 86000 cm³

Volume of water flowed in from Tap F
= 17 x 4000
= 68000 cm³

Volume of water from drained from Tap G
= 15 x 2000
= 30000 cm³

Volume of water left in the tank
= 68000 - 30000
= 38000 cm³

Base area of the tank
= 86000 ÷ 50
= 1720 cm² 

Height of water left in the tank
= 38000 ÷ 1720
≈ 22.1 cm

Answer(s): 22.1 cm