The engineering team needs to build a 250-kilometer road, 30 kilometers a day for the first 3 days, and if the rest is 40 kilometers a day, how many days will it take to finish it?
工程队要修一条长250千米的公路，前3天每天修30千米，剩下的如果每天修40千米，还要几天才能修完？
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">250 - 90</gadget>
<output>160</output>

<gadget id="calculator">160 / 40</gadget>
<output>4</output>

<result>4</result>