Parking in a parking lot costs at least 6 yuan once. If you park for more than 3 hours, you will have to pay an additional 2.5 yuan for each additional hour. How much does it cost to park a car in this parking lot for 10 hours?
在一个停车场停车一次至少要交费6元．如果停车超过3小时，每多停一小时要多交2.5元．一辆汽车在这个停车场停了10小时，需要交费多少元钱？
<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">2.5 * 7</gadget>
<output>17.5</output>

<gadget id="calculator">17.5 + 6</gadget>
<output>23.5</output>

<result>23.5</result>