A water reservoir initially contains 100 tone of water. Over a period of time 60 tonne of water flow into the reservoir. 20 tonne of water flow out of the reservoir and 3 tonne of water lost from the reservoir by evaporation. Water is not involved in any chemical reactions in the reservoir. What is the amount of water in the reservoir at the end of the period of time? (Answer In tones of water). Draw free body diagram, and define the control volume(s), and write the mass balance equation(s)?