The sum of the upper and lower bases of a trapezoid is 50 cm, and the height is 6 cm. What is the area of the trapezoid?
一个梯形的上，下底之和是50厘米，高是6厘米，这个梯形的面积是多少．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * 50 * 6</gadget>
<output>150</output>

<result>150</result>