Two people, A and B, surround a vegetable garden with wires of the same length, A makes a square and B makes a rectangle. Given that one side of the rectangle is 3 meters longer than the side of the square, how many square meters is the difference in area between the two vegetable gardens?
甲、乙两人用同样长度的铁丝围菜园，甲围成正方形，乙围成长方形．已知长方形一边比正方形的边长多3米，则两个菜园的面积相差多少平方米？
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