Master Li drives from place A to place B at 70 kilometers per hour, and it takes 4 hours to get there. If it is changed to 80 kilometers per hour, how many hours can Master Li reach?
李师傅开车从甲地到乙地，每小时行70千米，4小时可到达．如果改为每小时行80千米，李师傅多少小时可到达？
<gadget id="calculator">4 / 80</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">70 * (1/20)</gadget>
<output>7/2 = around 3.5</output>

<result>7/2 = around 3.5</result>