Question
An empty rectangular tank has a capacity of 135 ℓ and a height of 15 cm. At 7 a.m., Tap Q is turned on to fill the tank at a rate of 9 ℓ per minute for 20 minutes. After 15 minutes, Tap R is turned on to drain water from the tank at a rate of 7 ℓ per minute for 25 minutes. What is the height of the water level in the tank in the end? Give the answer in 1 decimal place.
3 m

Click button first when a symbol is required. X

An empty rectangular tank has a capacity of 135 ℓ and a height of 15 cm. At 7 a.m., Tap Q is turned on to fill the tank at a rate of 9 ℓ per minute for 20 minutes. After 15 minutes, Tap R is turned on to drain water from the tank at a rate of 7 ℓ per minute for 25 minutes. What is the height of the water level in the tank in the end? Give the answer in 1 decimal place.