The length of a classroom is 9 meters, the width is 7 meters, and the height is 3 meters. Now it is necessary to paint the roof and walls (the area of doors, windows and blackboards is 28 square meters), and the average cost of materials per square meter is 4.5 yuan. How much is the total labor cost for painting this classroom?
一间教室的长是9米，宽是7米，高是3米，现在要粉刷屋顶和墙壁(门窗和黑板的面积是28平方米)，平均每平方米需要工料费4.5元．粉刷这间教室一共需要工料费多少元？
<gadget id="calculator">9 * 7</gadget>
<output>63</output>

<gadget id="calculator">9 * 3 * 2</gadget>
<output>54</output>

<gadget id="calculator">7 * 3 * 2</gadget>
<output>42</output>

<gadget id="calculator">63 + 54 + 42</gadget>
<output>159</output>

<gadget id="calculator">159 - 28</gadget>
<output>131</output>

<gadget id="calculator">4.5 * 131</gadget>
<output>589.5</output>

<result>589.5</result>