Question 863487
let x = a dimension of a rectangle
let y = the dimension of a rectangle at right angle to x
let p = perimeter
let A = area
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Formula for rectangle perimeter:  {{{p=2(x+y)}}}
Formula for area of a rectangle:  {{{xy=A}}}


Assuming the given variables are p, A, and the unknown variables x and y and these need to be solved,

{{{y=A/x}}}.
Substitute into perimeter equation;
{{{p=2(x+(A/x))}}}
{{{2(x^2+A)/x=p}}}
{{{2(x^2+A)=px}}}
{{{2x^2+2A=px}}}
{{{highlight_green(2x^2-px+2A=0)}}}-----   This is only part way to the completed solution. 
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 Note certain things:


This is a quadratic equation, still in symbolic form;
A formula for x can be solved using the general solution to a quadratic equation;
If you substitute the given values NOW, you will probably learn that the quadratic expression will be factorable;
You still need to solve for y.