Selling 13 of a commodity at a profit of 7 yuan each costs as much as selling 12 at a profit of 11 yuan each. How much is the purchase price of this commodity.
某商品按每个7元的利润卖出13个的钱与每个11元的利润卖出12个的钱一样多．这种商品的进货价是每个多少元．
<gadget id="calculator">11 * 12</gadget>
<output>132</output>

<gadget id="calculator">7 * 13</gadget>
<output>91</output>

<gadget id="calculator">132 - 91</gadget>
<output>41</output>

<gadget id="calculator">13 - 12</gadget>
<output>1</output>

<gadget id="calculator">41 / 1</gadget>
<output>41</output>

<result>41</result>