The parking lot regulations of Jianghuai Mall: The parking lot charges 5 yuan for 2 hours; if it exceeds 2 hours, you will pay 1.5 yuan for each additional hour. The driver Xiao Liu paid a total of 15.5 yuan for parking when he drove away his car. How many hours did his car park there at most?
江淮商城的停车场规定：停车场计时收费5元2小时；超过2小时，每多停1小时再付1.5元．司机小刘开走他的车时共交了15.5元停车费，他的车在那最多停了几小时？
<gadget id="calculator">15.5 - 5</gadget>
<output>10.5</output>

<gadget id="calculator">10.5 / 1.5</gadget>
<output>7</output>

<gadget id="calculator">7 + 2</gadget>
<output>9</output>

<result>9</result>