A puddle is 0.06 meters deep after 1 hour and 0.03 meters deep after 5 hours. At what rate, in m/h, is the level of water changing

Assuming it's a constant rate, there is a four hour difference from t=1 and t=5, so subtract the difference in depth (0.03 - 0.06) and divide that by four.

-0.03/4 = -0.0075
So your change in depth in feet per hour is -0.0075.