Solve the following problem:
Q: A heat exchanger is used to cool an air flow from 800 to 360K, both states at 1 MPa. The coolant is a water flow at 15°C, 0.1 MPa. If the water leaves as saturated vapor, find the ratio of the flow rates mH2O/mair. You must solve the given problem step by step and also you need to include all the units which are needed to accomplish the given problem.