The sum of the upper and lower bases of the trapezoid is 18 decimeters, and the height is 7 decimeters. What is the area of the parallelogram formed by two such trapezoids?
梯形上底与下底的和是18分米，高是7分米，两个这样的梯形拼成的平行四边形的面积是多少平方分米．
<gadget id="calculator">7 / 2</gadget>
<output>7/2 = around 3.5</output>

<gadget id="calculator">18 * (7/2)</gadget>
<output>63</output>

<gadget id="calculator">63 * 2</gadget>
<output>126</output>

<result>126</result>