The figure is not drawn to scale. Tank H measuring 55 cm by 45 cm by 17 cm contained 21.9 ℓ of water. Tank J measuring 40 cm by 25 cm by 37 cm contained 17 ℓ of water. John poured some water from Tank H into Tank J without spilling and the water level of Tank J rose to 29 cm. What was the height of water level left in Tank H?
1 ℓ = 1000 cm³
17 ℓ = 17000 cm³
21.9 ℓ = 21.9 x 1000 = 21900 cm³

Height of water in Tank J at first
= 17000 ÷ 40 ÷ 25
= 17 cm

Increase in the height of water in Tank J
= 29 - 17
= 12 cm

Volume of water poured into Tank J
= 40 x 25 x 12
= 12000 cm³ 

Volume of water left in Tank H
= 21900 - 12000
= 9900 cm³ 

Height of water left in Tank H
= 9900 ÷ 55 ÷ 45
= 4 cm

Answer(s): 4 cm