There are 5 tricycles and cars with 18 wheels. How many cars are there?
三轮车和小汽车共5辆，18个轮子．小汽车有多少辆．
<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">18 - 15</gadget>
<output>3</output>

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

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

<result>3</result>