A rectangular iron sheet with a width of 20 cm is cut off from its four corners to form a square with a side length of 5 cm, and then welded into a rectangular box. If the volume of this box is 1300 cubic centimeters, what is the area of the original iron sheet?
一个宽为20厘米的长方形铁皮，把它四个角分别剪去一个边长为5厘米的正方形，然后焊接成一只长方体盒子．如果这只盒子的体积是1300立方厘米，原来铁皮的面积是多少平方厘米？
<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">20 - 10</gadget>
<output>10</output>

<gadget id="calculator">5 * 10</gadget>
<output>50</output>

<gadget id="calculator">1_300 / 50</gadget>
<output>26</output>

<gadget id="calculator">26 + 10</gadget>
<output>36</output>

<gadget id="calculator">36 * 20</gadget>
<output>720</output>

<result>720</result>