Zhang, Wang, and Li, Zhang and Wang travel from A to B, and Li travels from B to A. Zhang's speed is 21 kilometers per hour, Wang's speed is 27 kilometers per hour, and Li's speed is 15 kilometers per hour. ． The distance between A and B is 44 km. After a few hours, Wang happened to be between Zhang and Li.
张、王、李三人，张、王两人从A到B，李从B到A，张的速度每小时21千米，王的速度每小时27千米，李的速度每小时15千米．A、B两地之间距离44千米．多少小时后王正好在张、李的中间．
<gadget id="calculator">15 - 21</gadget>
<output>-6</output>

<gadget id="calculator">27 + 27 + (-6)</gadget>
<output>48</output>

<gadget id="calculator">44 / 48</gadget>
<output>11/12 = around 0.916667</output>

<result>11/12 = around 0.916667</result>