The figure is not drawn to scale. Tank A measuring 55 cm by 46 cm by 12 cm contained 35.71 ℓ of water. Tank B measuring 40 cm by 25 cm by 37 cm contained 12 ℓ of water. Bryan poured some water from Tank A into Tank B without spilling and the water level of Tank B rose to 30 cm. What was the height of water level left in Tank A?
1 ℓ = 1000 cm³
12 ℓ = 12000 cm³
35.71 ℓ = 35.71 x 1000 = 35710 cm³

Height of water in Tank B at first
= 12000 ÷ 40 ÷ 25
= 12 cm

Increase in the height of water in Tank B
= 30 - 12
= 18 cm

Volume of water poured into Tank B
= 40 x 25 x 18
= 18000 cm³ 

Volume of water left in Tank A
= 35710 - 18000
= 17710 cm³ 

Height of water left in Tank A
= 17710 ÷ 55 ÷ 46
= 7 cm

Answer(s): 7 cm