One wall of my house is 9 meters long and 4 meters high. Excluding the area occupied by doors and windows of 12 square meters, how many square meters is the actual wall to be painted?
我家的一面墙长9米，高4米，除去门窗占的面积12平方米，要粉刷这面墙实际是多少平方米？
<gadget id="calculator">9 * 4</gadget>
<output>36</output>

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

<result>24</result>