It has been 3 days to build a 1,500-meter-long road, with an average of 240 meters per day. How many meters are left to be repaired?
修一条长1500米的路，已经修了3天，平均每天修240米，还剩多少米没有修？
<gadget id="calculator">3 * 240</gadget>
<output>720</output>

<gadget id="calculator">1_500 - 720</gadget>
<output>780</output>

<result>780</result>