The perimeter of a rectangle is three times the perimeter of another square. It is known that the width of the rectangle and the side length of the square are both 9 decimeters. How many decimeters is the length of the rectangle?
一个长方形的周长是另一个正方形周长的3倍，已知长方形的宽与正方形的边长都是9分米，求长方形的长是多少分米？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<gadget id="calculator">36 * 3</gadget>
<output>108</output>

<gadget id="calculator">108 / 2</gadget>
<output>54</output>

<gadget id="calculator">54 - 9</gadget>
<output>45</output>

<result>45</result>