So I initially set the problem up as V=0.5bhl (where b=width, h=height, and l=length).

Then I took the derivative of both sides & found

dv/dt=0.5bl(dh/dt)

From here I plugged in the numbers 0.2=0.5(10)(6)(dh/dt)

& found dh/dt=1/150.

However, I don't have a place to plug height in for 2m. So would it be correct to reason dh/dt is independent from the height? Or do I have something incorrect in my setup?