There is a rectangle with a length of 20 cm and a width of 15 cm, which can be divided into 3 or 4 small rectangles by 2 straight lines parallel to the border of the rectangle. What is the maximum sum of the perimeters of these small rectangles?
有一个长20厘米、宽15厘米的长方形，用2条平行于长方形边界的直线可以将其划分成3个或4个小长方形．这些小长方形周长之和最大是多少厘米？
<gadget id="calculator">20 + 15</gadget>
<output>35</output>

<gadget id="calculator">4 * 35</gadget>
<output>140</output>

<result>140</result>