The sum of the upper and lower bases of a right-angled trapezoid is 16 cm, and the two sides are 7 cm and 5 cm respectively. What is the area of this trapezoid in square centimeters?
一个直角梯形上下底的和是16厘米，两条腰分别是7厘米和5厘米，这个梯形的面积是多少平方厘米．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">16 * (5/2)</gadget>
<output>40</output>

<result>40</result>