A car travels from A to B at 45 kilometers per hour and arrives in 4 hours. When returning, the speed increases to 60 kilometers per hour, so how many hours will it take to return to A?
汽车从甲地开往乙地，每小时行45千米，4小时到达．返回时速度增加到每小时60千米，这样需要几小时才能回到甲地？
<gadget id="calculator">4 / 60</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">45 * (1/15)</gadget>
<output>3</output>

<result>3</result>