The figure is not drawn to scale. Tank M measuring 50 cm by 45 cm by 20 cm contained 25.35 ℓ of water. Tank N measuring 42 cm by 25 cm by 33 cm contained 21 ℓ of water. Reggie poured some water from Tank M into Tank N without spilling and the water level of Tank N rose to 27 cm. What was the height of water level left in Tank M?
1 ℓ = 1000 cm³
21 ℓ = 21000 cm³
25.35 ℓ = 25.35 x 1000 = 25350 cm³

Height of water in Tank N at first
= 21000 ÷ 42 ÷ 25
= 20 cm

Increase in the height of water in Tank N
= 27 - 20
= 7 cm

Volume of water poured into Tank N
= 42 x 25 x 7
= 7350 cm³ 

Volume of water left in Tank M
= 25350 - 7350
= 18000 cm³ 

Height of water left in Tank M
= 18000 ÷ 50 ÷ 45
= 8 cm

Answer(s): 8 cm