There is a mountain road between A and B, with a distance of 60 kilometers. Part of it is an uphill road, and the rest is a downhill road. A person rides an electric bicycle from A to B, and then returns along the original road. It takes 4.5 hours to go and return. It took 3.5 hours. It is known that the downhill road is 20 kilometers per hour, how many kilometers per hour is the uphill road?
A、B两地之间是山路，相距60千米，其中一部分是上坡路，其余是下坡路，某人骑电动车从A地到B地，再沿原路返回，去时用了4.5小时，返回时用了3.5小时．已知下坡路每小时行20千米，那么上坡路每小时行多少千米？
<gadget id="calculator">4.5 + 3.5</gadget>
<output>8</output>

<gadget id="calculator">60 / 20</gadget>
<output>3</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<gadget id="calculator">60 / 5</gadget>
<output>12</output>

<result>12</result>