A canteen plans to burn 8,400 kilograms of coal per month. After improving the coal stove, it can save 40 kilograms of coal per day. According to this calculation, how many days can the original planned monthly coal consumption last? (A month is calculated as 30 days)
一个食堂每月计划烧煤8400千克，改进煤灶后每天可以节约用煤40千克，照这样计算，原计划每月的烧煤量可以烧几天？(一个月按30天计算)
<gadget id="calculator">8_400 / 30</gadget>
<output>280</output>

<gadget id="calculator">280 - 40</gadget>
<output>240</output>

<gadget id="calculator">8_400 / 240</gadget>
<output>35</output>

<result>35</result>