By selling an article for Rs. 100, a man gains Rs. 15. Then his gain percent is

\par S.P. = Rs. 100, gain = Rs. 15

\par C.P. = Rs. (100 - 15) = Rs. 85

\par Gain\% = \left(\frac{15}{85}\times 100)\right)\% =  \frac{300}{17}\% = 17\frac{11}{17}\%