The length of a classroom is 8 meters, the width is 6 meters, and the height is 3.5 meters. The walls and roof of the classroom need to be painted, and the area of the classroom is 24.5 square meters excluding the doors, windows and blackboard. If the paint fee is 4 yuan per square meter, paint this classroom How much does it cost?
一间教室的长是8米，宽是6米，高是3.5米，要粉刷教室的四壁和屋顶，除去门窗和黑板面积24.5平方米，如果每平方米需要4元涂料费，粉刷这个教室需要花费多少元？
<gadget id="calculator">8 * 6</gadget>
<output>48</output>

<gadget id="calculator">8 * 3.5 * 2</gadget>
<output>56</output>

<gadget id="calculator">6 * 3.5 * 2</gadget>
<output>42</output>

<gadget id="calculator">48 + 56 + 42</gadget>
<output>146</output>

<gadget id="calculator">146 - 24.5</gadget>
<output>121.5</output>

<gadget id="calculator">121.5 * 4</gadget>
<output>486</output>

<result>486</result>