The upper base of a trapezoid is 5cm, the lower base is 8cm, and the height is 2.4cm. What is the area of the trapezoid in cm**2.
一个梯形的上底是5cm，下底是8cm，高是2.4cm，这个梯形的面积是多少cm**2．
<gadget id="calculator">5 + 8</gadget>
<output>13</output>

<gadget id="calculator">2.4 / 2</gadget>
<output>1.2</output>

<gadget id="calculator">13 * 1.2</gadget>
<output>15.6</output>

<result>15.6</result>