The average of the upper and lower bases of a trapezoid is 50 cm and the height is 12 cm. What is its area in square centimeters?
一个梯形上、下底的平均数为50厘米，高12厘米，它的面积是多少平方厘米．
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">50 * 2 * 6</gadget>
<output>600</output>

<result>600</result>