A car travels from place A to place B for 4.5 hours, with an average of 80 kilometers per hour. It only takes 3.6 hours to return from place B to place A. How many kilometers per hour is the average speed when returning?
一辆汽车从甲地到乙地，行了4.5小时，平均每小时行80千米，从乙地返回甲地时只用了3.6小时，返回时平均每小时行多少千米？
<gadget id="calculator">4.5 / 3.6</gadget>
<output>1.25</output>

<gadget id="calculator">80 * 1.25</gadget>
<output>100</output>

<result>100</result>