By selling 33 metres of cloth a trader loses an amount equal to the selling price of 3 metres. His loss percent is:

Let the SP be 1 unit per metre. Total SP = 33 units and the loss = 3 units, so CP = 33 + 3 = 36 units. Loss % $=3/36\times 100=8.33$%. (Dividing the loss by the selling price gives 3/33 = 9.09% — loss percent is always on cost.)