def _Backward2c_T_Ps(P, s):
    """Backward equation for region 2c, T=f(P,s)

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

    Returns
    -------
    T : float
        Temperature [K]

    References
    ----------
    IAPWS, Revised Release on the IAPWS Industrial Formulation 1997 for the
    Thermodynamic Properties of Water and Steam August 2007,
    http://www.iapws.org/relguide/IF97-Rev.html, Eq 27

    Examples
    --------
    >>> _Backward2c_T_Ps(20,5.75)
    697.992849
    >>> _Backward2c_T_Ps(80,5.75)
    949.017998
    """
    I = [-2, -2, -1, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5,
         5, 6, 6, 7, 7, 7, 7, 7]
    J = [0, 1, 0, 0, 1, 2, 3, 0, 1, 3, 4, 0, 1, 2, 0, 1, 5, 0, 1, 4, 0, 1, 2,
         0, 1, 0, 1, 3, 4, 5]
    n = [0.90968501005365e3, 0.24045667088420e4, -0.59162326387130e3,
         0.54145404128074e3, -0.27098308411192e3, 0.97976525097926e3,
         -0.46966772959435e3, 0.14399274604723e2, -0.19104204230429e2,
         0.53299167111971e1, -0.21252975375934e2, -0.31147334413760,
         0.60334840894623, -0.42764839702509e-1, 0.58185597255259e-2,
         -0.14597008284753e-1, 0.56631175631027e-2, -0.76155864584577e-4,
         0.22440342919332e-3, -0.12561095013413e-4, 0.63323132660934e-6,
         -0.20541989675375e-5, 0.36405370390082e-7, -0.29759897789215e-8,
         0.10136618529763e-7, 0.59925719692351e-11, -0.20677870105164e-10,
         -0.20874278181886e-10, 0.10162166825089e-9, -0.16429828281347e-9]

    Pr = P/1
    sigma = s/2.9251
    T = 0
    for i, j, ni in zip(I, J, n):
        T += ni * Pr**i * (2-sigma)**j
    return T