A snail crawls upwards at the bottom of a well 12 meters deep. It climbs 3 meters per hour and then slides down 2 meters. How long does it take for the cow to climb out of the well?
一只蜗牛在12米深的井底向上爬，每小时爬上3米后要滑下2米，这只牛多少小时才能爬出井口．
<gadget id="calculator">9 / 1</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<result>10</result>