def formula(individu, period, parameters):
    """
        Revenus agricoles
        """
    frag_exon = individu('frag_exon', period)
    frag_impo = individu('frag_impo', period)
    arag_exon = individu('arag_exon', period)
    arag_impg = individu('arag_impg', period)
    arag_defi = individu('arag_defi', period)
    nrag_exon = individu('nrag_exon', period)
    nrag_impg = individu('nrag_impg', period)
    nrag_defi = individu('nrag_defi', period)
    nrag_ajag = individu('nrag_ajag', period)
    return (frag_exon + frag_impo + arag_exon + arag_impg - arag_defi +
        nrag_exon + nrag_impg - nrag_defi + nrag_ajag)
