There are 6 bicycles and tricycles with 13 wheels. How much more bicycles are there than tricycles?
自行车和三轮车共6辆，有13个轮子，自行车的数量比三轮车的数量多多少辆．
<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<gadget id="calculator">13 - 12</gadget>
<output>1</output>

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

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

<gadget id="calculator">6 - 1 - 1</gadget>
<output>4</output>

<result>4</result>