Posted by Richard Steele on .
A farmer has 100 yards of fencing to form two identical rectangular pens and a third pen that is twice as long as the other two pens, as shown in the diagram to the right. All three pens have the same width, x. Which value of y produces the maximum total fenced area?

12th grade algebra 
PsyDAG,
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We do not have your diagram, so we don't know if they have common fences.