The sixth grade students of Yucai School went to the countryside for a spring outing on foot. The students from class 19 formed the front team with a walking speed of 4 kilometers per hour, and the students from class 20 formed the rear team with a walking speed of 6 kilometers per hour. One hour after the front team set off, The rear team started, and at the same time, the rear team sent a liaison officer to communicate back and forth between the two teams on a bicycle. She was riding at a speed of 12 kilometers per hour. When the rear team was chasing the front team, the liaison officer sent by the rear team Constantly communicate back and forth between the two teams, so when the liaison officer catches up with the front team for the first time, he goes back and forth. When he meets the back team, how far is the back team from the starting point?
育才学校六年级的学生步行去郊外春游，19班学生组成前队，步行速度为4千米每小时，20班学生组成后队，步行速度为6千米每小时，前队出发1小时后，后队才出发，同时后队派一名联络员骑自行车在两队之间不断来回联络，她骑车的速度为12千米每小时，后队在追前队时，后队派的联络员在两队之间不停地来回联络，那么当联络员第一次追上前队后，往回返，当他和后队相遇时，后队离出发地有多远？
<gadget id="calculator">12 - 4</gadget>
<output>8</output>

<gadget id="calculator">4 / 8</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">4 * (1/2)</gadget>
<output>2</output>

<gadget id="calculator">6 * (1/2)</gadget>
<output>3</output>

<gadget id="calculator">2 - 3</gadget>
<output>-1</output>

<gadget id="calculator">4 + (-1)</gadget>
<output>3</output>

<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<gadget id="calculator">3 / 18</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/2) + (1/6)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) * 6</gadget>
<output>4</output>

<result>4</result>