A truck travels from A to B at 60 kilometers per hour and arrives in just 6 hours. When I came back, I went back the same way, and I just returned to Jiadi in 4.5 hours. How many kilometers per hour did you drive when you returned? (answer with ratio)
一辆卡车从甲地开往乙地，每小时行驶60千米，6小时刚好到达．回来时原路返回，4.5小时刚好回到甲地．返回时每小时行驶多少千米？(用比例解答)
<gadget id="calculator">60 * 6</gadget>
<output>360</output>

<gadget id="calculator">360 / 4.5</gadget>
<output>80</output>

<result>80</result>