A certain parking lot charge regulations: charge 2.5 yuan within 1 hour, and charge 2.5 yuan every half hour after more than 1 hour. When Uncle Li picks up his car in this parking lot, he pays a parking fee of 12.5 yuan. How many hours has Uncle Li's car been parked?
某停车场收费规定：1小时内收2.5元，超过1小时后，每半小时收2.5元．李叔叔到这个停车场取车时，交停车费12.5元，李叔叔的车停了多少小时．
<gadget id="calculator">12.5 - 2.5</gadget>
<output>10</output>

<gadget id="calculator">2.5 / 0.5</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

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

<result>3</result>