Question 982506
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(6yds-x)(12yds-x)=40yds^2
72yds-6xyds-12xyds+x^2=40yds^2
x^2-18xyds+72yds^2=40yds^2
x^2-18xyds+32yds=0
(x-2yds)(x-16yds)=0
x-2yds=0 OR x-16yds=0
x=2yds OR x=16yds x=16yds results in negative measurements, so
x=2 yards ANSWER: The border can be 2 yards wide.