To erect a communication line, it is planned to erect 80 meters per day and be completed in 25 days. If 100 meters per day is erected, how many days in advance can it be completed? (Solve it in two ways, one of which is a proportional solution)
要架设一条通讯线路，计划每天架设80米，25天完成，如果每天架设100米，可提前多少天完成？(用两种方法解，其中一种用比例解)
<gadget id="calculator">25 * 100</gadget>
<output>2_500</output>

<gadget id="calculator">25 * 80</gadget>
<output>2_000</output>

<gadget id="calculator">2_500 - 2_000</gadget>
<output>500</output>

<gadget id="calculator">500 / 100</gadget>
<output>5</output>

<result>5</result>