Change in rate of duty

excise duty is chargable whenever it is removed from factory

ex : if on the date of manufacture the rate is 10 %

      and on the date of removal the rate is 12 %

      for this question the applicable rate is 12 % 

                      but

      if it is given in the question as the rate of duty on the date of manufacture i.e., 20.06.2013 is 12%                           on the date of removal i.e., 25.09.2013 is 12 % + Addl.duty @ 6 % imposed w.e.f 01.07.2013      

     what would be the excise duty payable in the above question ? (is it only 12 % or 12 % + 6 %) ?

     please clarify....