Annuities - Calculate nominal rate of interest

So I am not sure where to begin on this question.

A furniture store advertises that you can pay either no tax or no interest. The terms of the no tax option are that no tax will be charged if you pay for your purchase in full on the purchase date. The terms of the no interest option are that you will be charged the 14% tax and pay for your purchase with equal payments at the end of each month for 1 year. Calculate the nominal rate of interest compounded monthly being charged on the "no interest" option.

Any help guys?