Hi

Let the price of 16 articles be 100 rupees

Gain=35%

Selling price of 15 articles be = 100 x 100+35/100=Rs.135

Marked price of 15 articles x (100-4)/100=rs.135

Marked price of 15 articles= 135 x 100/(100-4)= 140.625

Cost price of 15 articles = 100 x 15/16 = 93.75

Required increment = (140.625 - 93.75) x 100/93.75 = 50%

Marked price is 50% more than the cost price.

Hope this information is helpful.