One pot can bake 2 cakes at the same time, each side takes 3 minutes, how many minutes is the minimum time to bake 5 cakes.
一个锅一次能同时烙2个饼，两面各需要3分钟，烙5个饼最少需要多少分钟．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">6 + 9</gadget>
<output>15</output>

<result>15</result>