The figure is not drawn to scale. K and L are two containers. The base area of K is 10 cm² while the base area of L is 40 cm². Container K and L contained some water and the height of the water level in Container K was 70 cm as shown. Dan then poured some water from Container K into Container L. After that, the height of the water level in both tanks became 30 cm. What was the height of the water level in Container L at first?
Change in the water level of Container K
= 70 - 30
= 40 cm

Volume of water poured in the Container L
= 10 x 40
= 400 cm³ 

Height increase in Container L
= 400 ÷ 40
= 10 cm

Original height of the water in Container L
= 30 - 10
= 20 cm

Answer(s): 20 cm