Use 120 cm long iron wire to form a rectangle. If the length is 42 cm, how many cm should be the width? (solution by equation)
用120厘米长的铁丝，围成一个长方形，要使长是42厘米，宽应该是多少厘米？(用方程解)
<gadget id="calculator">42 * 2</gadget>
<output>84</output>

<gadget id="calculator">120 - 84</gadget>
<output>36</output>

<gadget id="calculator">36 / 2</gadget>
<output>18</output>

<result>18</result>