A train travels 360 km, 90 km per hour, 4 hours, 80 km per hour, how many hours?
一列火车行驶360km，每小时行驶90km，要行4小时，每小时行80km，要行多少小时？
<gadget id="calculator">360 / 80</gadget>
<output>9/2 = around 4.5</output>

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