Buy 1 Get 2(1 formal dress +1 sample)

Buy 2 get 4(2 formal clothes +2 small samples)

Buy 3 get 6(3 formal clothes +3 samples)

Buy 4 get 8(4 formal clothes +4 samples)

Buy 5 get 10(5 formal clothes +5 samples)

Buy 6 get 12(6 formal clothes +6 samples)

Buy 7 and get 14(7 formal clothes +7 samples)