Every time you make a call to a certain place, you have to pay at least 0.8 yuan each time. If it exceeds 3 minutes, an additional 0.3 yuan will be paid for every 1 minute exceeded. Xiao Ming made a call to a certain place and paid 2.9 yuan. How many minutes did he call?
打某地电话每次至少要交费0.8元．如果超过3分钟，每超过1分钟再交0.3元．小明打一次到某地的电话，交费2.9元，他打了几分钟的电话？
<gadget id="calculator">2.9 - 0.8</gadget>
<output>2.1</output>

<gadget id="calculator">2.1 / 0.3</gadget>
<output>7</output>

<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<result>10</result>