An empty rectangular tank has a capacity of 98 ℓ and a height of 100 cm. At 10 a.m., Tap L is turned on to fill the tank at a rate of 9 ℓ per minute for 15 minutes. After 13 minutes, Tap M is turned on to drain water from the tank at a rate of 9 ℓ per minute for 11 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 
9 ℓ = 9000 cm³ 
9 ℓ = 9000 cm³ 
98 ℓ = 98000 cm³

Volume of water flowed in from Tap L
= 15 x 9000
= 135000 cm³

Volume of water from drained from Tap M
= 11 x 9000
= 99000 cm³

Volume of water left in the tank
= 135000 - 99000
= 36000 cm³

Base area of the tank
= 98000 ÷ 100
= 980 cm² 

Height of water left in the tank
= 36000 ÷ 980
≈ 36.7 cm

Answer(s): 36.7 cm