A butterfly flies 15.6 kilometers in 0.5 hours, and a bee flies 19.5 kilometers per hour. How much less does the bee fly than the butterfly?
一只蝴蝶0.5小时飞行15.6千米，一只蜜蜂每小时飞行19.5千米，蜜蜂比蝴蝶每小时少飞行多少千米？
<gadget id="calculator">15.6 / 0.5</gadget>
<output>31.2</output>

<gadget id="calculator">31.2 - 19.5</gadget>
<output>11.7</output>

<result>11.7</result>