If the height of a triangle is kept constant and the base is extended by 4 meters, the area will increase by 10 square meters. If the base remains the same and the height is extended by 3 meters, the area will be increased by 12 square meters. What is the area of the original triangle in square meters?
一个三角形如果高不变底延长4米，面积就增加10平方米，如果底不变，高延长3米，面积就增加12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">12 * (2/3)</gadget>
<output>8</output>

<gadget id="calculator">2 / 4</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">10 * (1/2)</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>