A box of biscuits is 30 centimeters long, 15 centimeters wide, and 20 centimeters high. Now it is necessary to stick label paper around it. If the joint of the label paper is 3 cm, what is the area of the label paper in square centimeters?
一盒饼干长30厘米，宽15厘米，高20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3厘米，这张商标纸的面积是多少平方厘米？
<gadget id="calculator">20 * 30</gadget>
<output>600</output>

<gadget id="calculator">15 * 20</gadget>
<output>300</output>

<gadget id="calculator">600 + 300</gadget>
<output>900</output>

<gadget id="calculator">900 * 2</gadget>
<output>1_800</output>

<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">1_800 + 60</gadget>
<output>1_860</output>

<result>1_860</result>