In Wang Xiaohua's house, one wall is 3 meters high and 5 meters long, and there is a window with an area of 3 square meters. If Wang Xiaohua wants to paint this wall, please help Wang Xiaohua calculate the area of the part to be painted.
王小花家有一面墙高3米，长5米，其中有个窗子面积为3平方米．如果王小花要粉刷这面墙，请你帮王小花算一算要粉刷部分的面积．
<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<result>12</result>