From A to B, it takes Xiao Hong 12 hours, and Xiao Gang takes 15 hours. Xiao Gang's speed is Xiao Hong's.
从甲地到乙地，小红要用12小时，小刚要用15小时，小刚的速度是小红的多少．
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/15) / (1/12)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>