The figure is not drawn to scale. Tank R measuring 48 cm by 45 cm by 21 cm contained 22.96 ℓ of water. Tank S measuring 40 cm by 25 cm by 34 cm contained 21 ℓ of water. Zeph poured some water from Tank R into Tank S without spilling and the water level of Tank S rose to 31 cm. What was the height of water level left in Tank R?
1 ℓ = 1000 cm³
21 ℓ = 21000 cm³
22.96 ℓ = 22.96 x 1000 = 22960 cm³

Height of water in Tank S at first
= 21000 ÷ 40 ÷ 25
= 21 cm

Increase in the height of water in Tank S
= 31 - 21
= 10 cm

Volume of water poured into Tank S
= 40 x 25 x 10
= 10000 cm³ 

Volume of water left in Tank R
= 22960 - 10000
= 12960 cm³ 

Height of water left in Tank R
= 12960 ÷ 48 ÷ 45
= 6 cm

Answer(s): 6 cm