Elite Primary School decided to paint the classrooms of Grade 1 during the summer vacation. The length, width, and height of each classroom are 8m, 5m, and 4m respectively. In addition, the sum of the doors and windows of the classroom is 21 square meters, and the price of the paint is per square meter. It costs 4 yuan. How much does it cost to renovate a classroom?
精英小学决定在暑假中为1年级教室涂涂料，每个教室的长、宽、高分别是8m、5m、4m，另外教室门窗的面积之和为21平方米，而涂料的价格为每平方米需4元．请问，一个教室的装修需要花费多少钱？
<gadget id="calculator">8 * 5</gadget>
<output>40</output>

<gadget id="calculator">5 * 4 * 2</gadget>
<output>40</output>

<gadget id="calculator">8 * 4 * 2</gadget>
<output>64</output>

<gadget id="calculator">64 - 21</gadget>
<output>43</output>

<gadget id="calculator">40 + 40 + 43</gadget>
<output>123</output>

<gadget id="calculator">123 * 4</gadget>
<output>492</output>

<result>492</result>