A pan can only bake two cakes at a time, and each side is baked for 3 minutes. What is the minimum time to bake 5 cakes in this way?
一只锅每次只能烙两张饼，每面烙3分钟，这样烙好5张饼最少的时间是多少分钟．
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<result>15</result>