A piece of iron wire just surrounds a square with a side length of 7 decimeters. If it is used to make a rectangular support with a length of 9 decimeters, how wide is this support?
一根铁丝刚好围边长7分米的正方形一周，如用来做一个长9分米的长方形支架，这个支架有多宽？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<gadget id="calculator">14 - 9</gadget>
<output>5</output>

<result>5</result>