Uncle Wang spent 3 hours driving from place A to place B, traveling 50km per hour, and 60km per hour when returning. How many hours did it take to return?
王叔叔开车从甲地到乙地一共用了3小时，每小时行50km，返回时每小时行60km，返回时用了多少小时？
<gadget id="calculator">3 / 60</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">50 * (1/20)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>