Aunt Zhang uses a frying pan to cook cakes, and puts up to 4 cakes in the pan at a time. It takes 3 minutes to bake one cake on each side, and how many minutes does it take to bake 6 cakes at least.
张阿姨用平底锅烙饼，锅中每次最多放4张饼，烙一个饼每面需3分钟，烙6张饼至少需要多少分钟．
<gadget id="calculator">3 + 3 + 3</gadget>
<output>9</output>

<result>9</result>