Use a tape measure to circle around the classroom. It is 30 meters long. The length of the classroom is 8 meters. What is the area of the classroom in square meters?
用卷尺沿教室的四周绕一圈，是30米，已知教室的长是8米，教室的面积是多少平方米？
<gadget id="calculator">30 / 2</gadget>
<output>15</output>

<gadget id="calculator">15 - 8</gadget>
<output>7</output>

<gadget id="calculator">8 * 7</gadget>
<output>56</output>

<result>56</result>