From Yiwu to Chi'an, Xiao Ming ran for 1.8 hours, and Qiao Dan ran for 1.5 hours. How much slower is Xiao Ming's speed than Qiao Dan?
从义乌到赤岸，小明跑步用了1.8小时，巧丹跑步用了1.5小时，小明的速度比巧丹慢多少？
<gadget id="calculator">1 / 1.5</gadget>
<output>0.666667</output>

<gadget id="calculator">1 / 1.8</gadget>
<output>0.555556</output>

<gadget id="calculator">0.666667 - 0.555556</gadget>
<output>0.111111</output>

<gadget id="calculator">0.111111 / 0.666667</gadget>
<output>0.166666</output>

<result>0.166666</result>