A car travels from A to B at a speed of 85 km/h and arrives in 8 hours. It took 10 hours to return from point B to point A because of the rain. What is the average speed of the car in km/h when returning?
一辆汽车以85千米/小时的速度从甲地开往乙地，8小时到达．从乙地返回甲地，因为下雨用了10小时．这辆汽车返回时的平均速度是多少千米/小时？
<gadget id="calculator">8 / 10</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">85 * (4/5)</gadget>
<output>68</output>

<result>68</result>