A 60 cm long iron wire surrounds it into a rectangle with a length of 18 cm. What is the width of this rectangle?
一根长60厘米的铁丝，把它围成一个长18厘米的长方形，这个长方形的宽应是多少厘米？
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">30 - 18</gadget>
<output>12</output>

<result>12</result>