If the Dry bulb reads 25 degrees Celsius and the wet bulb reads 22
degrees Celsius. Is the relative humidity high or low? How do you know?

Relative humidity is low .

Explanation:

The wet bulb reads low temperature because due to low humidity of atmosphere , evaporation of water takes place from the wet bulb which makes the bulb cool and therefore it reads lower temperature . In the process of evaporation , heat equal to latent heat of vaporization is taken from the bulb and it loses temperature.