The base length of a triangle is 8 meters. If the base is extended by 1 meter, the area will increase by 2.5 square meters. Please find out the area of the original triangle in square meters?
一个三角形的底长是8米，如果底边延长1米，那么面积就增加2.5平方米，请你求出原来三角形的面积是多少平方米？
<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">2.5 * 2</gadget>
<output>5</output>

<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">8 * (5/2)</gadget>
<output>20</output>

<result>20</result>