classroom is 10 meters long, 8 meters wide, and 4 meters high. The total area of doors and windows is 20 square meters. If you want to paint the walls and ceiling of this classroom, how many square meters is the area to be painted?
一间教室长10米，宽8米，高4米，门窗总面积是20平方米，要粉刷这间教室的四壁和顶面，要粉刷的面积是多少平方米？
<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">40 + 32</gadget>
<output>72</output>

<gadget id="calculator">72 * 2</gadget>
<output>144</output>

<gadget id="calculator">144 - 20</gadget>
<output>124</output>

<gadget id="calculator">80 + 124</gadget>
<output>204</output>

<result>204</result>