A road of 1500 meters is built, and after some days, there are still 600 meters left. How many meters were repaired? (use x)
修一条1500米的路，修了一些天后还剩600米．修了多少米？(用x)
<gadget id="calculator">1_500 - 600</gadget>
<output>900</output>

<result>900</result>