The ratio of length to width of a rectangle is 7:3. If the length is reduced by 12 cm and the width is increased by 16 cm, it becomes exactly a square. What is the area of the rectangle in square centimeters?
一个长方形的长与宽的比是7：3，如果把长减少12厘米，宽增加16厘米，正好变成一个正方形，这个长方形的面积是多少平方厘米？
<gadget id="calculator">12 + 16</gadget>
<output>28</output>

<gadget id="calculator">7 - 3</gadget>
<output>4</output>

<gadget id="calculator">28 / 4</gadget>
<output>7</output>

<gadget id="calculator">7 * 7</gadget>
<output>49</output>

<gadget id="calculator">49 - 28</gadget>
<output>21</output>

<gadget id="calculator">49 * 21</gadget>
<output>1_029</output>

<result>1_029</result>