The upper base of a trapezoid is 2 decimeters, the lower base is 6 decimeters, and the height is 4.5 decimeters. What is its area in square decimeters?
一个梯形的上底是2分米，下底是6分米，高是4.5分米，它的面积是多少平方分米．
<gadget id="calculator">2 + 6</gadget>
<output>8</output>

<gadget id="calculator">4.5 / 2</gadget>
<output>2.25</output>

<gadget id="calculator">8 * 2.25</gadget>
<output>18</output>

<result>18</result>