car travels from city A to city B at 45 kilometers per hour and arrives in 5 hours. When returning, drive 50 kilometers per hour, how many hours to return to Jiacheng? (Solve with ratio)
一辆汽车从甲城开往乙城，每小时行45千米，5小时到达．返回时，每小时行驶50千米，几小时回到甲城？(用比例解)
<gadget id="calculator">45 * 5</gadget>
<output>225</output>

<gadget id="calculator">225 / 50</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>