Xiaoming’s house needs to paint a wall. The length of this wall is 9 meters and the height is 4 meters. Excluding the area occupied by doors and windows of 12 square meters, how many square meters do you actually need to paint?
小明家要粉刷一面墙，这面墙的长是9米，高是4米，除去门窗占的面积12平方米，实际要粉刷多少平方米？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

<gadget id="calculator">36 - 12</gadget>
<output>24</output>

<result>24</result>