The upper base of a trapezoid is 5 cm. If the upper base is lengthened by 3 cm, it becomes a square. What is the area of the trapezoid in square centimeters?
一个梯形的上底是5厘米，如果上底加长3厘米就变成了一个正方形，这个梯形的面积是多少平方厘米．
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">5 + 8</gadget>
<output>13</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">13 * 4</gadget>
<output>52</output>

<result>52</result>