1. The problem statement, all variables and given/known data A reservoir of square cross-section has sides sloping at an angle of 45 degrees with the vertical. The side of the bottom is p feet in length, and water flows in the reservoir at the rate of c cubic feet per minute. Find an expression for the rate at which the surface of the water is rising at the instant its depth is h feet. Calculate this rate when p = 17, h = 4 and c = 35. 2. Relevant equations Not stated 3. The attempt at a solution I don't know how to begin, I'm sorry.