A wire can form a square with a side length of 8 decimeters. Now use it to surround a rectangle. If the width of this rectangle is 7 decimeters, how many decimeters is the length?
一根铁丝可以围成一个边长8分米的正方形，现在用它来围一个长方形，如果这个长方形的宽是7分米，那么长是多少分米？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">8 * 2</gadget>
<output>16</output>

<gadget id="calculator">16 - 7</gadget>
<output>9</output>

<result>9</result>