The sum of the upper and lower bases of a trapezoid is 4 decimeters, and the height is (4/5) decimeters. What is the area of the trapezoid in square decimeters?
一个梯形上底与下底的和是4分米，高是(4/5)分米，这个梯形的面积是多少平方分米．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(4/5) / 2</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">4 * (2/5)</gadget>
<output>8/5 = around 1.6</output>

<result>8/5 = around 1.6</result>