The road construction team has to build a road with a length of 2640 meters, and the average daily repair is 90 meters in the first 20 days. If the remaining 15 meters are repaired every day, how many days will it take to complete the repair?
修路队要修一条长2640米的路，前20天平均每天修90米．余下的如果每天修15米，那么还要几天修完？
<gadget id="calculator">20 * 90</gadget>
<output>1_800</output>

<gadget id="calculator">2_640 - 1_800</gadget>
<output>840</output>

<gadget id="calculator">840 / 15</gadget>
<output>56</output>

<result>56</result>