A car drives from place A to place B, travels 50 kilometers per hour, and arrives in 4.2 hours. It only took 3.5 hours to return, what was the speed of the car when it returned?
一辆汽车从甲地开往乙地，去时每小时行50千米，4.2小时可以到达．返回时只用了3.5小时，汽车返回时的速度是多少？
<gadget id="calculator">4.2 / 3.5</gadget>
<output>1.2</output>

<gadget id="calculator">50 * 1.2</gadget>
<output>60</output>

<result>60</result>