An empty rectangular tank has a capacity of 160 ℓ and a height of 40 cm. At 9 a.m., Tap Z is turned on to fill the tank at a rate of 10 ℓ per minute for 20 minutes. After 13 minutes, Tap A is turned on to drain water from the tank at a rate of 7 ℓ per minute for 6 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 
10 ℓ = 10000 cm³ 
7 ℓ = 7000 cm³ 
160 ℓ = 160000 cm³

Volume of water flowed in from Tap Z
= 20 x 10000
= 200000 cm³

Volume of water from drained from Tap A
= 6 x 7000
= 42000 cm³

Volume of water left in the tank
= 200000 - 42000
= 158000 cm³

Base area of the tank
= 160000 ÷ 40
= 4000 cm² 

Height of water left in the tank
= 158000 ÷ 4000
≈ 39.5 cm

Answer(s): 39.5 cm