Teacher Zhang attended the meeting. From home to the venue, it takes 17 minutes to ride a bicycle when you come, and ride a motorcycle when you go back; if you ride a motorcycle back and forth, it only takes 12 minutes. How many minutes does it take Mr. Zhang to ride his bicycle back and forth?
张老师参加会议．从家到会场，来时骑自行车，回去骑摩托车，共用17分钟；如果来回都骑摩托车，只要12分钟．张老师来回都骑自行车需要多少分钟．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">17 - 6</gadget>
<output>11</output>

<gadget id="calculator">11 * 2</gadget>
<output>22</output>

<result>22</result>