Uncle Fang drove to the county seat at a speed of 80km per hour for 3 hours, and when he returned, he drove 90km per hour. How much time did he spend on the return? (Answer with the knowledge of proportion)
方叔叔开车去县城以每小时80km的速度，行了3小时，返回时每小时行90km，返回时少用了多少时间？(用比例的知识解答)
<gadget id="calculator">80 * 3</gadget>
<output>240</output>

<gadget id="calculator">240 / 90</gadget>
<output>8/3 = around 2.666667</output>

<gadget id="calculator">3 - (8/3)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>