The stationery store originally had 660 pencils, but after selling some, there are still 300 pencils left. There are 12 pencils in each box, how many boxes are sold in total?
文具店原有660支铅笔，卖出一些后，还剩下300支．每盒铅笔装12支，一共卖出多少盒？
<gadget id="calculator">660 - 300</gadget>
<output>360</output>

<gadget id="calculator">360 / 12</gadget>
<output>30</output>

<result>30</result>