Uncle Wang drove from A to B, originally planned to travel 84km per hour, so it would take 5 o'clock to arrive; actually traveled 120km per hour, so how much earlier than the original plan to arrive at B?
王叔叔开车从甲地到乙地，原计划每小时行84km，这样需要5时才能到达；实际每时行120km，这样比原计划提前多少时到达乙地？
<gadget id="calculator">5 / 120</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">84 * (1/24)</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">5 - (7/2)</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>