In a parking lot, there are a total of 30 vehicles, among which the cars have 4 wheels and the motorcycles have 3 wheels. These vehicles have 100 wheels in total, so how many three-wheeled motorcycles are there?
在一个停车场，共有30辆车，其中汽车是4个轮子，摩托车是3个轮子，这些车共有100个轮子，那么三轮摩托车有多少辆．
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">100 - 90</gadget>
<output>10</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<gadget id="calculator">10 / 1</gadget>
<output>10</output>

<gadget id="calculator">30 - 10</gadget>
<output>20</output>

<result>20</result>