It is known that the upper base of the trapezoid is 5.4 decimeters, the lower base is 3.2 decimeters, and the height is 3 decimeters. Find the area of this trapezoid.
已知梯形的上底是5.4分米，下底是3.2分米，高是3分米．求这个梯形的面积．
<gadget id="calculator">5.4 + 3.2</gadget>
<output>8.6</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">8.6 * (3/2)</gadget>
<output>12.9</output>

<result>12.9</result>