The base length of a triangle is 10 meters. If the base is extended by 3 meters, the area will increase by 8.7 square meters. How many square meters is the area of the original triangle?
一个三角形的底长是10米，如果底边延长3米，那么面积就增加8.7平方米，原来三角形的面积是多少平方米？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">8.7 * (2/3)</gadget>
<output>5.8</output>

<gadget id="calculator">5.8 / 2</gadget>
<output>2.9</output>

<gadget id="calculator">10 * 2.9</gadget>
<output>29</output>

<result>29</result>