Question 104654
The area of a rectangle is equal to A=L*W. 
The area of your rectangle is 36 sq.inches.
Your first equation is 
1. {{{A=LW=36}}}
You say that the length is 9 inches greater than the width, or
2.{{{L=9+W}}}
Substitute your equation (2) into (1) and solve for W.
{{{LW=36}}}
{{{(9+W)W=36}}}
{{{9W+W^2=36}}} Distributive property.
{{{W^2+9W-36=0}}} Additive inverse of 36. 
{{{(W+12)(W-3)=0}}} Factor the quadratic equation. 
Solutions are 
W=-12, W=3. 
Since a negative width does not make sense, we throw out that solution. 
W=3 inches
{{{L=9+W}}}
{{{L=9+3}}}
L=12 inches