The purchase price of a newspaper is 0.3 yuan per copy, and the retail price is 0.5 yuan per copy. Junjun earned 40 yuan by selling this newspaper on Sunday. How many copies of this newspaper did Junjun sell?
一种报纸进价每份0.3元，零售价每份0.5元，军军星期天卖这种报纸赚了40元，军军卖了多少份这种报纸？
<gadget id="calculator">0.5 - 0.3</gadget>
<output>0.2</output>

<gadget id="calculator">40 / 0.2</gadget>
<output>200</output>

<result>200</result>