car drives from point A to point B, and then returns from point B to point A. The round-trip speed ratio is 5:4. It takes 6 hours to go there. How many hours does it take to return? (Answer with the knowledge of proportion)
一辆汽车从A地开往B地，再从B地返回A地，往返的速度比是5：4，去时用6小时，返回时用了多少小时？(用比例的知识解答)
<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">30 / 4</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>