The driver, Uncle Wang, set off from Xiamen to deliver goods in Fuzhou. He drove for 4 hours at a speed of 60 km/h and arrived at a speed of 80 km/h when he returned. How long did it take to return?
司机王叔叔从厦门出发到福州送货，去时以60千米/时的速度行驶4小时到达，返回时以80千米/时速度原路返回，返回时用了几小时？
<gadget id="calculator">4 / 80</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">60 * (1/20)</gadget>
<output>3</output>

<result>3</result>