A butterfly flies 6.3 kilometers in 0.3 hours. How many kilometers does the butterfly fly per hour?
一只蝴蝶0.3小时飞行了6.3千米．这只蝴蝶每小时飞行多少千米．
<gadget id="calculator">6.3 / 0.3</gadget>
<output>21</output>

<result>21</result>