A trader purchases several articles at the rate of 13 for Rs. 10 and sells them at the rate of 10 for Rs. 13. What is his gain/loss?	Choose the correct choice from the following answers.
A) 68 % B) 69 % C) 66 % D) 63 % E) 29 %
Explanation:   We have, C. P of 13 articles = Rs. 10   &amp; S. P of 10 articles = Rs. 13   S. P of 13 articles = ?   = (13 * 13) / 10= 
<gadget id="calculator">(13 * 13) / 10</gadget>
<output>169/10 = around 16.9</output>
16.9   Gain= [(16.9 – 10)/10] * 100 = 69 %   ANSWER: 69 %
<result>B</result>
A trader purchases several articles at the rate of 13 for Rs. 10 and sells them at the rate of 10 for Rs. 13. What is his gain/loss?