A dry well is 230 cm deep. A snail climbs up 110 cm during the day and slides down 70 cm at night. Which day can this snail crawl out of the wellhead?
一口枯井深230厘米，一只蜗牛要从井底爬到井口处，它白天向上爬110厘米，而晚上却向下滑70厘米．这只蜗牛那一个白天才能爬出井口？
<gadget id="calculator">230 - 110</gadget>
<output>120</output>

<gadget id="calculator">110 - 70</gadget>
<output>40</output>

<gadget id="calculator">120 / 40</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>