A duck weighs 3 kg, and a sheep weighs 6 times as much. How much does a sheep weigh more than a duck?
一只鸭重3千克，一只羊的重量是它的6倍．羊比鸭重多少千克？
<gadget id="calculator">3 * 6</gadget>
<output>18</output>

<gadget id="calculator">18 - 3</gadget>
<output>15</output>

<result>15</result>