A flat-top classroom is 7.5 meters long, 6 meters wide, and 3 meters high. The classroom doors, windows and blackboards have a total area of 32.8 square meters. How many square meters will be painted on the top and four walls of the classroom?
一间平顶教室，长7.5米，宽是6米，高是3米，教室门窗和黑板的面积一共有32.8平方米．要粉刷教室的顶面和四面墙壁，粉刷的面积有多少平方米？
<gadget id="calculator">7.5 * 6</gadget>
<output>45</output>

<gadget id="calculator">7.5 * 3 * 2</gadget>
<output>45</output>

<gadget id="calculator">6 * 3 * 2</gadget>
<output>36</output>

<gadget id="calculator">36 - 32.8</gadget>
<output>3.2</output>

<gadget id="calculator">45 + 45 + 3.2</gadget>
<output>93.2</output>

<result>93.2</result>