By selling some goods at Rs. 31, a salesman loses 7% on his output. Find the percentage profit of loss, when he sells the same at Rs. 35 = ?

Selling price of goods = Rs. 31
Cost price of goods
$$\eqalign{ & = {\text{31}} \times \frac{{100}}{{93}} \cr & = {\text{Rs}}{\text{. }}\frac{{100}}{3} \cr & {\text{Profit }}\% \cr & = \frac{{35 - \frac{{100}}{3}}}{{\frac{{100}}{3}}} \times 100 \cr & = \frac{{\frac{5}{3}}}{{\frac{{100}}{3}}} \times 100 \cr & = 5\% \cr} $$