dragonfly flies 5.76 kilometers in 0.6 hours. Swallows fly 2.1 times faster than dragonflies. How many kilometers does the swallow fly per hour?
一只蜻蜓0.6小时飞行5.76千米．燕子飞行的速度是蜻蜓的2.1倍．燕子每小时飞行多少千米？
<gadget id="calculator">5.76 / 0.6</gadget>
<output>9.6</output>

<gadget id="calculator">9.6 * 2.1</gadget>
<output>20.16</output>

<result>20.16</result>