A trapezoid has a ratio of upper and lower bases of 4:9. If the upper base is increased by 11 cm and the lower base is decreased by 4 cm, it becomes a square. What is the area of the square?
一个梯形，它的上、下底之比是4：9，如果将上底增加11厘米，下底减少4厘米，就成为一个正方形，这个正方形的面积是多少？
<gadget id="calculator">11 + 4</gadget>
<output>15</output>

<gadget id="calculator">9 - 4</gadget>
<output>5</output>

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

<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">12 + 11</gadget>
<output>23</output>

<gadget id="calculator">23 * 23</gadget>
<output>529</output>

<result>529</result>