Let us suppose the cost of 1 metre cloth is Re 1.
cost of 11 metres is Rs. 11 and of 33 metres is Rs. 33.
On selling 33 metres of cloth, the person gains the cost of 11 metres
on selling 33 metres of cloth, the persons gains Rs. 11
since cost of 33 metres of cloth is Rs. 33, if on selling them the person gains Rs. 11 , it means he sold them for Rs. 44
gain % = gain/cost = 11/33 = 33.33%