The wall in front of the classroom is 6 meters long and 3 meters high. There is a blackboard with an area of 3.8 square meters on the wall. Now this wall is going to be painted, what is the area to be painted?
教室前面的墙壁，长6米，高3米．墙上有一块面积是3.8平方米的黑板．现在要粉刷这面墙，要粉刷的面积是多少？
<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">18 - 3.8</gadget>
<output>14.2</output>

<result>14.2</result>