biscuit box is 20 centimeters long, 18 centimeters wide, and 25 centimeters high. Now it is necessary to affix label paper around it. If the joint of the label paper is 4 cm, what is the area of the label paper in square decimeters?
一个饼干盒长20厘米，宽18厘米，高25厘米，现在要在它的四周贴上商标纸，如果商标纸的接头处是4厘米，这张商标纸的面积是多少平方分米？
<gadget id="calculator">20 * 25</gadget>
<output>500</output>

<gadget id="calculator">18 * 25</gadget>
<output>450</output>

<gadget id="calculator">500 + 450</gadget>
<output>950</output>

<gadget id="calculator">950 * 2</gadget>
<output>1_900</output>

<gadget id="calculator">25 * 4</gadget>
<output>100</output>

<gadget id="calculator">1_900 + 100</gadget>
<output>2_000</output>

<gadget id="calculator">2_000 / 100</gadget>
<output>20</output>

<result>20</result>