The Baineng Pen Factory has produced a batch of fountain pens, each packed in a box of 12, 80 boxes have been packed, and there are 3,000 pens left. Pack these fountain pens into three boxes respectively, how many pens are packed in each box on average?
百能笔厂生产了一批水笔，每12支装一盒，已经装了80盒，还剩3000支．把这批水笔分别装在三个箱子里，平均每箱装多少支？
<gadget id="calculator">12 * 80</gadget>
<output>960</output>

<gadget id="calculator">960 + 3_000</gadget>
<output>3_960</output>

<gadget id="calculator">3_960 / 3</gadget>
<output>1_320</output>

<result>1_320</result>