Two people, A and B, are running on a track. A is 12 meters away from the finish line, and B is 36 meters away from the finish line. When A arrives, B is still 28 meters away. Find the length of the runway.
甲乙两人在某跑道上比赛跑步，甲离终点12米，乙离终点36米，当甲到时，乙还差28米，求跑道长．
<gadget id="calculator">36 - 28</gadget>
<output>8</output>

<gadget id="calculator">12 / 8</gadget>
<output>3/2 = around 1.5</output>

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

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">28 / (1/3)</gadget>
<output>84</output>

<result>84</result>