A bicycle and a car are traveling from A to B at the same time. The car travels 40 kilometers per hour, and the bicycle travels 10 kilometers per hour. After 10 hours, the car arrives at B and immediately returns on the same road. Encounter, how many hours does it take from departure at the same time to encounter?
一辆自行车和一辆汽车同时从甲地向乙地行驶，汽车每小时行40千米，自行车每小时行10千米，行了10小时汽车到达乙地，马上按原路返回，途中与自行车相遇，求从同时出发到相遇共用多少小时？
<gadget id="calculator">40 + 10</gadget>
<output>50</output>

<gadget id="calculator">2 / 50</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">40 * 10 * (1/25)</gadget>
<output>16</output>

<result>16</result>