classroom with a length of 9 meters, a width of 6 meters, and a height of 4 meters is painted on its roof and walls. If the area of doors and windows is 24 meters**2, if 200 grams of wall powder is used per square meter, how many kilograms of wall powder are needed in total? ?
一间长9米，宽6米，高4米的教室，粉刷它的屋顶和墙壁，扣除门窗面积24米**2，如果每平方米用刷墙粉200克，一共需要刷墙粉多少千克？
<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<gadget id="calculator">9 * 4</gadget>
<output>36</output>

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

<gadget id="calculator">54 + 36 + 24</gadget>
<output>114</output>

<gadget id="calculator">114 * 2</gadget>
<output>228</output>

<gadget id="calculator">228 - 54 - 24</gadget>
<output>150</output>

<gadget id="calculator">200 / 1_000</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">150 * (1/5)</gadget>
<output>30</output>

<result>30</result>