Spring is here, Xiaoming, Xiaodong and Xiaoqiang went to the suburbs to catch butterflies, Xiaoming caught 3, Xiaodong caught 5, they caught 12 in total, how many did Xiaoqiang catch?
春天来了，小明、小冬和小强到郊外捉蝴蝶，小明捉了3只，小冬捉了5只，他们一共捉了12只，小强捉了几只？
<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">12 - 8</gadget>
<output>4</output>

<result>4</result>