def _Backward2c_P_hs(h, s):
    """Backward equation for region 2c, P=f(h,s)

    Parameters
    ----------
    h : float
        Specific enthalpy, [kJ/kg]
    s : float
        Specific entropy, [kJ/kgK]

    Returns
    -------
    P : float
        Pressure, [MPa]

    References
    ----------
    IAPWS, Revised Supplementary Release on Backward Equations for Pressure
    as a Function of Enthalpy and Entropy p(h,s) for Regions 1 and 2 of the
    IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of
    Water and Steam, http://www.iapws.org/relguide/Supp-PHS12-2014.pdf, Eq 5

    Examples
    --------
    >>> _Backward2c_P_hs(2800,5.1)
    94.39202060
    >>> _Backward2c_P_hs(2800,5.8)
    8.414574124
    >>> _Backward2c_P_hs(3400,5.8)
    83.76903879
    """
    I = [0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 
        5, 5, 5, 5, 6, 6, 10, 12, 16]
    J = [0, 1, 2, 3, 4, 8, 0, 2, 5, 8, 14, 2, 3, 7, 10, 18, 0, 5, 8, 16, 18,
        18, 1, 4, 6, 14, 8, 18, 7, 7, 10]
    n = [0.112225607199012, -3.39005953606712, -32.0503911730094, -
        197.5973051049, -407.693861553446, 13294.3775222331, 
        1.70846839774007, 37.3694198142245, 3581.44365815434, 
        423014.446424664, -751071025.760063, 52.3446127607898, -
        228.351290812417, -960652.417056937, -80705929.2526074, 
        1626980172256.69, 0.772465073604171, 46392.9973837746, -
        13731788.5134128, 1704703926305.12, -25110462818730.8, 
        31774883083552.0, 53.8685623675312, -55308.9094625169, -
        1028615.22421405, 2042494187562.34, 273918446.626977, -
        2639631463126850.0, -1078908541.08088, -29649262098.0124, -
        1117549073234240.0]
    nu = h / 3500
    sigma = s / 5.9
    suma = 0
    for i, j, ni in zip(I, J, n):
        suma += ni * (nu - 0.7) ** i * (sigma - 1.1) ** j
    return 100 * suma ** 4
