A: Yes—you did everything right identifying the two state points and finding the intersection using mass-weighted enthalpy. That approach is valid and leads to the correct answer. The method in the solution is just one path; mass flow rate–weighted mixing via enthalpy and specific volume is a legitimate alternative.

A: That approach does work for finding dry bulb temperature, but finding dew point by going horizontally left from a dry bulb/wet bulb point requires that you're already on the saturation curve—you can't go 'left to find dew point' from an interior point. The more reliable method is to use the humidity ratio, find it on the vertical axis, and move horizontally to the saturation curve; that intersection gives you the dew point temperature directly. Both approaches should agree if executed correctly, but the humidity ratio method is more straightforward.

A: Using the humidity ratio is the more reliable method for finding dew point because dew point corresponds to a fixed humidity ratio—you find that value on the vertical axis and trace horizontally to the saturation curve. Tracing from a wet bulb/dry bulb intersection can introduce chart-reading error, especially when the mixed conditions are in a crowded region of the psychrometric chart. Both methods are correct in theory, but the humidity ratio approach is more accurate in practice.