The sum of the upper and lower bases of a trapezoid is 70 cm, and the height is 14 cm. What is the area of the trapezoid in square centimeters?
一个梯形的上、下底的和是70厘米，高是14厘米，这个梯形的面积是多少平方厘米．
<gadget id="calculator">14 / 2</gadget>
<output>7</output>

<gadget id="calculator">70 * 7</gadget>
<output>490</output>

<result>490</result>