Question 1132749
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The fence, making 3 sides of the field, has a total length of 320 yards; the perimeter of the whole rectangular field is 400 yards.  So the length of the field along the wall is 400-320 = 80 yards.<br>
So one dimension of the field is 80 yards.  That makes 2 sides of length 80, for a total of 160 yards.<br>
Since the perimeter of the whole field is 400 yards, the sum of the lengths of the other two sides is 400-160 = 240 yards.  So the other dimension of the field is 240/2 = 120 yards.<br>
ANSWER: 80 by 120 yards