Bake a cake on the stove. Both sides of the cake must be baked, and each side needs to be baked for 5 minutes. Only two cakes can be placed on the stove at the same time. Now you need to bake three cakes, how many minutes will it take at least.
在火炉上烤饼，饼的两面都要烤，每烤一面要5分钟，炉上只能同时放两块饼．现在需要烤三张饼，最少需要多少分钟．
<gadget id="calculator">5 + 5 + 5</gadget>
<output>15</output>

<result>15</result>