Uncle Wang drove a pickup truck from Zoucheng to Jinan to buy goods. The space-time car travels 90 kilometers per hour and arrives in 2 hours. On the return trip, due to the load, it can only travel 60 kilometers per hour. How many hours will it take to return to Zoucheng? (Solution with proportional knowledge)
王叔叔开一辆小货车从邹城去济南进货．去时空车每小时行90千米，2小时到达．返回时由于载货，每小时只能行60千米，需要多少小时返回邹城？(用比例知识解)
<gadget id="calculator">90 * 2</gadget>
<output>180</output>

<gadget id="calculator">180 / 60</gadget>
<output>3</output>

<result>3</result>