right-angled trapezoid, the ratio of the upper base to the lower base is 3:5, if the upper base is increased by 7 cm, and the lower base is increased by 1 cm, it becomes a square. What is the area of the trapezoid in square centimeters?
一个直角梯形，上底与下底的比是3：5，如果把上底增加7厘米，下底增加1厘米，就变成了一个正方形．求梯形的面积是多少平方厘米？
<gadget id="calculator">7 - 1</gadget>
<output>6</output>

<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">5 * 3</gadget>
<output>15</output>

<gadget id="calculator">9 + 15</gadget>
<output>24</output>

<gadget id="calculator">9 + 7</gadget>
<output>16</output>

<gadget id="calculator">16 / 2</gadget>
<output>8</output>

<gadget id="calculator">24 * 8</gadget>
<output>192</output>

<result>192</result>