A canal is 6,400 meters in total. In the first three months, an average of 1,200 meters will be repaired each month. The rest will be completed within 2 months. How many meters should be completed on average each month?
一条水渠共6400米，前三个月平均每月修1200米，余下的要在2个月内完成，平均每月至少要完成多少米？
<gadget id="calculator">1_200 * 3</gadget>
<output>3_600</output>

<gadget id="calculator">6_400 - 3_600</gadget>
<output>2_800</output>

<gadget id="calculator">2_800 / 2</gadget>
<output>1_400</output>

<result>1_400</result>