If a pan can fry 2 pancakes at a time, both sides must be pan-fried, and each side takes 4 minutes, how many minutes will it take to pan-fry 5 pancakes?
如果一个平底锅一次可以煎2个饼，两面都要煎，每煎一面要4分钟，煎5个饼要多少分钟．
<gadget id="calculator">4 + 4</gadget>
<output>8</output>

<gadget id="calculator">4 * 3</gadget>
<output>12</output>

<gadget id="calculator">8 + 12</gadget>
<output>20</output>

<result>20</result>