Question: Temperature-humidity index the temperature humidity index (THI) is given by
THI = t - 0.55(1 - h)(t - 58)
where t is the air temperature in degrees Fahrenheit and h is the relative humidity. If the THI remains constant, find the rate of change of humidity with respect to temperature if the temperature is 70°F (Source: "Temperature-Humidity Indices," UMAP Journal, Fall 1989).