The cross-section of a sewer is trapezoidal, the width of the sewer is 2.8 meters, the bottom width of the sewer is 1.2 meters, and the depth of the sewer is 1.6 meters. How many square meters is its cross-sectional area?
一条下水道的横截面是梯形，下水道的宽是2.8米，下水道的底宽是1.2米，下水道的深是1.6米，它的横截面面积是多少平方米？
<gadget id="calculator">2.8 + 1.2</gadget>
<output>4</output>

<gadget id="calculator">1.6 / 2</gadget>
<output>0.8</output>

<gadget id="calculator">4 * 0.8</gadget>
<output>3.2</output>

<result>3.2</result>