A line is 500m long and is advancing at a speed of 80m/min. Due to an emergency, the correspondent ran from the end of the line to the head of the line at a speed of 120m/min, and then immediately returned from the head to the end of the line. How many m has the team advanced during this time?
一列队伍长500m，正以80m/min的速度前进，因有事通讯员以120m/min的速度跑步从排尾追到排头，又立即从排头回到排尾．这段时间队伍前进了多少m？
<gadget id="calculator">120 - 80</gadget>
<output>40</output>

<gadget id="calculator">500 / 40</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">120 + 80</gadget>
<output>200</output>

<gadget id="calculator">500 / 200</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">(25/2) + (5/2)</gadget>
<output>15</output>

<gadget id="calculator">80 * 15</gadget>
<output>1_200</output>

<result>1_200</result>