Question 823868
?

x and y are the dimensions of the rectangle.
{{{xy=81}}} and 2x+2y=30 which means, {{{x+y=15}}}.


More than one way to go from there...


y=15-x;
x(15-x)=81
15x-x^2=81
x^2-15x+81=0 seems not factorable.

x=(15+sqrt(15^2-4*81))/(2), contains imaginary component.


Either I made a fundamental mistake or your situation described is impossible.