A classroom is 8.5 meters long, 6 meters wide, and 4 meters high. The total area of doors, windows and blackboards is 35.8 square meters. To paint this classroom, how many square meters will be painted?
一间教室长8.5米，宽6米，高4米．门窗和黑板的面积一共有35.8平方米．要粉刷这间教室，粉刷的面积有多少平方米？
<gadget id="calculator">8.5 * 4</gadget>
<output>34</output>

<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<gadget id="calculator">34 + 24</gadget>
<output>58</output>

<gadget id="calculator">2 * 58</gadget>
<output>116</output>

<gadget id="calculator">8.5 * 6</gadget>
<output>51</output>

<gadget id="calculator">51 - 35.8</gadget>
<output>15.2</output>

<gadget id="calculator">116 + 15.2</gadget>
<output>131.2</output>

<result>131.2</result>