There are 13 four-wheeled vehicles and two-wheeled motorcycles in the parking lot, and there are 36 wheels. How many motorcycles are there?
停车场有四轮车和两轮摩托车共13辆，轮子共有36个，摩托车有多少辆．
<gadget id="calculator">13 * 2</gadget>
<output>26</output>

<gadget id="calculator">36 - 26</gadget>
<output>10</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

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

<gadget id="calculator">13 - 5</gadget>
<output>8</output>

<result>8</result>