Question 955843
Draw a rectangle with with two segments vertically, forming the three equal partitions of the region.  Call the horizontal distance or dimension, x; and call the vertical dimension, y.


AREA:  xy=18000
FENCE MATERIAL:  2x+2y+y+y=920


{{{system(xy=18000,2x+4y=920)}}}


Skipping over a few steps,....
{{{(460-2y)y=18000}}}
{{{(230-y)y=9000}}}
.
{{{y^2-230y+9000=0}}}
-
The discriminant of the quadratic equation is....   {{{(130)^2}}}.  You would continue with the general solution formula and say  {{{highlight(y=(230+- 130)/2)}}}.


Trying the MINUS form just to take a value,
{{{highlight(y=50)}}};
The other dimension, {{{x=460-2y}}},
{{{highlight(x=360)}}}.


Using the PLUS form,
finding that {{{highlight(y=180)}}}__________{{{highlight(x=100)}}}.


Both combinations will work.