A salesman can earn 6.5 yuan for every hour he works. In addition, he can get a bonus of 2.5 yuan for every transaction he makes. He earned a total of 212.5 yuan in a certain week, and made 7 transactions, how many hours did he work this week?
推销员每工作1小时可以挣6.5元，另外，每做成一次交易他可以得2.5元的奖金．某个星期他共收入212.5元，其中做成了7次交易，他这个星期工作了多少小时？
<gadget id="calculator">2.5 * 7</gadget>
<output>17.5</output>

<gadget id="calculator">212.5 - 17.5</gadget>
<output>195</output>

<gadget id="calculator">195 / 6.5</gadget>
<output>30</output>

<result>30</result>