A square frame with an edge length of 8 cm is just welded with an iron wire. If this iron wire is welded into a rectangular parallelepiped frame with a length of 13 cm and a height of 4 cm, how many centimeters should its width be?
用一根铁丝刚好焊接成一个棱长为8厘米的正方体框架，如果用这根铁丝焊接成一个长13厘米，高4厘米的长方体框架，它的宽应是多少厘米？
<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<gadget id="calculator">8 * 3</gadget>
<output>24</output>

<gadget id="calculator">13 + 4</gadget>
<output>17</output>

<gadget id="calculator">24 - 17</gadget>
<output>7</output>

<result>7</result>