One wall of the classroom is 8 meters long and 3 meters high. There are two windows with an area of 3 square meters on the wall. Now this wall is to be painted. How many square meters is the area to be painted?
教室一面墙壁长8米，高3米，墙上有2个面积各是3平方米的窗户，现在要粉刷这面墙壁，要粉刷的面积是多少平方米？
<gadget id="calculator">8 * 3</gadget>
<output>24</output>

<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">24 - 6</gadget>
<output>18</output>

<result>18</result>