An isosceles trapezoid is surrounded by an iron wire with a length of 12.4 decimeters. It is known that the two sides of the trapezoid are 6.4 decimeters long and the height is 9 decimeters. What is the area of the trapezoid in square decimeters?
用一根长12.4分米的铁丝围成一个等腰梯形，已知这个梯形的两腰共长6.4分米，高是9分米，这个梯形的面积是多少平方分米？
<gadget id="calculator">4.6 * 2</gadget>
<output>9.2</output>

<gadget id="calculator">12.4 - 9.2</gadget>
<output>3.2</output>

<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">3.2 * (9/2)</gadget>
<output>14.4</output>

<result>14.4</result>