store sells 387 pairs of cashmere trousers, and there are 405 pairs left. How many more pieces will be sold so that the number sold will be as many as the remaining ones?
某商店卖出绒裤387条，还剩下405条．再卖出多少条，卖出的数量就和剩下的数量同样多？
<gadget id="calculator">387 + 405</gadget>
<output>792</output>

<gadget id="calculator">792 / 2</gadget>
<output>396</output>

<gadget id="calculator">396 - 387</gadget>
<output>9</output>

<result>9</result>