An empty rectangular tank has a capacity of 131 ℓ and a height of 200 cm. At 8 a.m., Tap R is turned on to fill the tank at a rate of 6 ℓ per minute for 15 minutes. After 4 minutes, Tap S is turned on to drain water from the tank at a rate of 5 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 
6 ℓ = 6000 cm³ 
5 ℓ = 5000 cm³ 
131 ℓ = 131000 cm³

Volume of water flowed in from Tap R
= 15 x 6000
= 90000 cm³

Volume of water from drained from Tap S
= 8 x 5000
= 40000 cm³

Volume of water left in the tank
= 90000 - 40000
= 50000 cm³

Base area of the tank
= 131000 ÷ 200
= 655 cm² 

Height of water left in the tank
= 50000 ÷ 655
≈ 76.3 cm

Answer(s): 76.3 cm