conference room is 10m long, 8m wide, and 4m high, with a total area of 50m for doors and windows**2. If the walls and ceiling are painted, an average of 0.25 kg of paint is used per square meter, and 20 yuan per kilogram of paint. How much will it cost to paint this conference room?
一间会议室长10m，宽8m，高4m，门窗面积共50m**2．如果粉刷墙壁和顶棚，平均每平方米用涂料0.25㎏，每千克涂料20元．粉刷这间会议室一共要花费多少元涂料费？
<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<gadget id="calculator">10 * 4</gadget>
<output>40</output>

<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">40 + 32</gadget>
<output>72</output>

<gadget id="calculator">72 * 2</gadget>
<output>144</output>

<gadget id="calculator">144 - 50</gadget>
<output>94</output>

<gadget id="calculator">80 + 94</gadget>
<output>174</output>

<gadget id="calculator">174 * 0.25 * 20</gadget>
<output>870</output>

<result>870</result>