Growth Rate from Temperature and Humidity

A researcher is studying the effects of temperature and humidity on plant growth. The relationship between these variables can be modeled by the linear function:

$$ G(t, h) = 2t + 3h - 10 $$

where G represents the growth rate in arbitrary units, t is the temperature in degrees Celsius, and h is the humidity percentage. What is the growth rate when the temperature is 25 degrees Celsius and the humidity is 60%?