Uncle workers want to build a 1,000-meter-long railway. In March, 381 kilometers were repaired, and in April, 599 kilometers were repaired. How many kilometers of railways are left to be repaired? (Calculated in two ways.)
工人叔叔要修一条1000米长的铁路，3月份修了381千米，4月份修了599千米，还有多少千米的铁路没修？(用两种方法计算．)
<gadget id="calculator">381 + 599</gadget>
<output>980</output>

<gadget id="calculator">1_000 - 980</gadget>
<output>20</output>

<result>20</result>