A car is originally planned to travel 70 kilometers per hour, and it takes 6 hours to travel from point A to point B. In fact, the car traveled 120 kilometers in 1.5 hours. According to this speed, how many hours earlier than the original plan from point A to point B? (Solve with direct and inverse proportion)
一辆汽车原计划每小时行驶70千米，从甲地到乙地需要行驶6小时，实际上这辆汽车1.5小时就行驶了120千米．照这样的速度，从甲地到乙地比原计划提前了几小时？(用正比例和反比例解)
<gadget id="calculator">70 * 6</gadget>
<output>420</output>

<gadget id="calculator">120 / 1.5</gadget>
<output>80</output>

<gadget id="calculator">420 / 80</gadget>
<output>21/4 = around 5.25</output>

<gadget id="calculator">6 - (21/4)</gadget>
<output>3/4 = around 0.75</output>

<result>3/4 = around 0.75</result>