def relative_f_to_c_degree(fahrenheit_degree):
    """
    Convert relative degrees Fahrenheit to Celsius
    For example, if I want to increase the thermostat 3 degrees F, then I need to adjust it 1.66668 degrees C.
    :param fahrenheit_degree: relative number of degrees F
    :return: relative number of degrees C
    """
    return float(fahrenheit_degree) * 0.555556