Uncle Wang divided a rectangular vegetable plot with a circumference of 120 meters among his three sons, and each of them got a small rectangular vegetable plot. The perimeter of the three small rectangles was 140 meters longer than before. What is the original area of the vegetable field in square meters?
王大伯把一个周长是120米的长方形菜地平均分给三个儿子，每人分得一个小长方形菜地，三个小长方形的周长比原来多了140米．原来菜地的面积是多少平方米？
<gadget id="calculator">120 / 2</gadget>
<output>60</output>

<gadget id="calculator">140 / 4</gadget>
<output>35</output>

<gadget id="calculator">60 - 35</gadget>
<output>25</output>

<gadget id="calculator">25 * 35</gadget>
<output>875</output>

<result>875</result>