Xiao Zhang, Xiao Wang, and Xiao Li started from the same place by the lake at the same time and walked around the lake. Zhang travels 5.4 km/h, Wang travels 4.2 km/h, Li walks 3 km/h in the opposite direction with them, and 5 minutes after Xiao Zhang meets Xiao Li, Xiao Li meets Xiao Wang. Then, the trip around the lake is How many kilometers.
小张、小王、小李三人同时从湖边同一地点出发，绕湖行走．张5.4千米/时，王4.2千米/小时，李与他们反向行走3千米/小时，小张与小李相遇后5分钟，小李与小王相遇，那么，绕湖一周行程是多少千米．
<gadget id="calculator">5.4 + 3</gadget>
<output>8.4</output>

<gadget id="calculator">4.2 + 3</gadget>
<output>7.2</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">7.2 * (1/12)</gadget>
<output>0.6</output>

<gadget id="calculator">5.4 - 4.2</gadget>
<output>1.2</output>

<gadget id="calculator">0.6 / 1.2</gadget>
<output>0.5</output>

<gadget id="calculator">8.4 * 0.5</gadget>
<output>4.2</output>

<result>4.2</result>