Xiaohua planned to do 80 math problems in 20 minutes, but actually did 1 more question per minute than planned. In fact, it only takes a few minutes to finish it?
小华计划20分钟做80道口算题，实际每分钟比计划多做1道，实际只要几分钟就可以做完？
<gadget id="calculator">80 / 20</gadget>
<output>4</output>

<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">80 / 5</gadget>
<output>16</output>

<result>16</result>