A 26-foot tall oil tank began the day completely full. ÿIt is being emptied into a transport truck at a constant rate. ÿThe depth of the oil in the tank is a function of the nummber of minutes the tank has been emptying. ÿThe equation y = 26 – (1/5)x ÿcan be used to determine y, the depth of oil remaining in the tank after x minutes. ÿDetermine the rate of change in this equation.