The school bought 12 boxes of ballpoint pens, 15 in each box, and spent a total of 720 yuan. How much is each ballpoint pen?
学校买进12盒圆珠笔，每盒15支，共花了720元，每支圆珠笔多少元？
<gadget id="calculator">15 * 12</gadget>
<output>180</output>

<gadget id="calculator">720 / 180</gadget>
<output>4</output>

<result>4</result>