Dongdong has to do 12 questions, including 3 subtraction questions, and 6 questions have been done, so how many questions is left for Dongdong to finish?
东东要做12道题，其中有3道减法，已经做了6道，那么东东还差几道做完？
<gadget id="calculator">12 - 6</gadget>
<output>6</output>

<result>6</result>