Teacher Li went from school to the Education Bureau for a meeting. When he set off, he looked at his watch and found that if he walked, he would be 6 minutes late; if he rode a bicycle, he could arrive 3 minutes earlier. It is known that Mr. Li walks at a speed of 100 m/min and rides a bicycle at a speed of 200 m/min. How long will it be before Mr. Li leaves?
李老师从学校到教育局开会，出发时他看了一下表，发现如果步行，他将迟到6分钟；如果骑自行车，可以提前3分钟到达．已知李老师步行速度是100米/分钟，骑自行车的速度是200米/分钟．李老师出发时离开会还有多长时间？
<gadget id="calculator">100 * 6</gadget>
<output>600</output>

<gadget id="calculator">200 * 3</gadget>
<output>600</output>

<gadget id="calculator">600 + 600</gadget>
<output>1_200</output>

<gadget id="calculator">200 - 100</gadget>
<output>100</output>

<gadget id="calculator">1_200 / 100</gadget>
<output>12</output>

<result>12</result>