To complete a communication line, it is planned to erect 80 meters per day and complete in 25 days. Now if 100 meters are erected every day, how many days can it be completed in advance?
要完成一条通讯线路，计划每天架设80米，25天完成．现如果每天架设100米，可以提前几天完成？
<gadget id="calculator">24 - 20</gadget>
<output>4</output>

<result>4</result>