please help me with the calculus homework question ASAP pleaseeeee help thank you

Question

An inverted pyramid is being filled with water at a constant rate of 70 cubic centimeters per second. The pyramid, at the top, has the shape of a square with sides of length 5 cm, and the height is 12 cm.

Find the rate at which the water level is rising when the water level is 8 cm.

Answer 1

Volume of a part of the cylinder is V = (1/3) x² h where x is the side length representing the top of the water. x and h are in the same ratio as 5:12, so replace x with (5/12) h, x² = (25/144) h². Now V = (1/3)(25/144) h³ and dV/dt = (25/144) h² dh/dt = 70 cm³ /s. At h = 8, dh/dt = 70 /(25*64/144) = 70 /(25*4/9) = 9*70/100 = 63/10 = 6.3 cm/s.