Xiaoming’s house needs to paint a wall. The length of this wall is 8 meters and the height is 3 meters. Excluding the area occupied by doors and windows of 9 square meters, how many square meters does it actually need to paint?
小明家要粉刷一面墙，这面墙的长是8米，高是3米，除去门窗占的面积9平方米，实际要粉刷多少平方米？
<gadget id="calculator">8 * 3</gadget>
<output>24</output>

<gadget id="calculator">24 - 9</gadget>
<output>15</output>

<result>15</result>