One parking lot. 2.5 yuan for 1 hour, 2.50 yuan for every 0.5 hours over 1 hour. Uncle Li paid 12.5 yuan for parking this time. How many hours did Uncle Li park in this parking lot this time?
一个停车场停车．1小时内收2.5元，超过1小时，每0.5小时收2.50元．李叔叔这次停车交了12.5元，李叔叔这次在这个停车场停车多少小时？
<gadget id="calculator">12.5 - 2.5</gadget>
<output>10</output>

<gadget id="calculator">10 / 2.5</gadget>
<output>4</output>

<gadget id="calculator">4 * 0.5</gadget>
<output>2</output>

<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<result>3</result>