Cut a square paper with a side length of 15 cm as shown in the figure, and cut it into 3 rectangular papers on average. What is the perimeter of each rectangular paper in centimeters?
将如图一张边长是15厘米的正方形纸，平均剪成3张长方形纸，每张长方形纸的周长是多少厘米．
<gadget id="calculator">15 + 5</gadget>
<output>20</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<result>40</result>