Related Rates: Word Problem. Help!

Hi reddit,

I have no idea what this question is describing. I need two diagrams, but I don't understand where the triangle cross-section comes in. Can anyone help me out?

Text:

Vancouver’s primary water source is melting snow in the North Shore water-sheds. Imagine one of the reservoirs that collects the water from this melting snow is 450 metres long, and its cross-section is an isosceles triangle 40 metres wide at the top and 20 √ 3 metres high. Water is flowing into the top of this reservoir at a rate of 200 cubic metres per hour and, simultaneously, water is leaking out from the bottom of the reservoir at the rate of 50 cubic metres per hour. Find the rate at which the water level is rising when the depth of the water is 10 √ 3 metres.

It may be useful for you to draw two diagrams: one of the reservoir and one of its triangular cross-section.