The school has to paint the classrooms. It is known that the length of the classroom is 7 meters, the width is 6 meters, the height is 3 meters, and the area after deducting the doors and windows is 11.4 square meters. If paint costs 5 yuan per square meter, how much will it cost to paint this classroom?
学校要粉刷教室．已知教室的长是7米，宽是6米，高是3米，扣除门窗面积是11.4平方米．如果每平方米需要花5元涂料费，粉刷这个教室需要花多少元？
<gadget id="calculator">7 * 6</gadget>
<output>42</output>

<gadget id="calculator">7 * 3</gadget>
<output>21</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">21 + 18</gadget>
<output>39</output>

<gadget id="calculator">39 * 2</gadget>
<output>78</output>

<gadget id="calculator">78 - 11.4</gadget>
<output>66.6</output>

<gadget id="calculator">42 + 66.6</gadget>
<output>108.6</output>

<gadget id="calculator">108.6 * 5</gadget>
<output>543</output>

<result>543</result>