Bingbing ran 4 times back and forth on a straight runway, a total of 720 meters. How long is this runway in meters?
冰冰在一条直跑道上跑了4个来回，一共跑了720米．这条跑道长多少米？
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">720 / 8</gadget>
<output>90</output>

<result>90</result>