Question 918107
You may want to answer the question, what are the dimensions of the rectangular shape to be fenced?


Here is the symbolized situation:


x and y are the dimensions.
xy=100 and either 2x+y=30 or x+2y=30.  Pick the length equation that you want; either dimension can be used at length or width as long as you stay consistent with your choice.


Taking {{{x+2y=30}}},
{{{x=30-2y}}};
substituting into the area equation,
{{{(30-2y)*y=100}}}
{{{30y-2y^2=100}}}
{{{15y-y^2=50}}}
{{{-y^2+15y-50=0}}}
{{{y^2-15y+50=0}}}
{{{highlight((y-10)(y-5)=0)}}}


You should be able to interpret what the final equation means...