def _Backward3_T_Ps(P, s):
    """Backward equation for region 3, T=f(P,s)

    Parameters
    ----------
    P : float
        Pressure, [MPa]
    s : float
        Specific entropy, [kJ/kgK]

    Returns
    -------
    T : float
        Temperature, [K]
    """
    sc = 4.41202148223476
    if s <= sc:
        T = _Backward3a_T_Ps(P, s)
    else:
        T = _Backward3b_T_Ps(P, s)
    return T