Question 698600
Let's use 2 equations for this, L is Length and W is Width: 
 2L+2W=480
 L(W)=10800 rewritten as: L=10800/W
 Use substitution for this:
 2(10800/W)+2W=480 or rewritten as: 21600/W+2W=480
 Multiply by W:
 21600+2w^2=480W

 

Divide by 2 and subtract 240W:
 W^2 -240W +10800 =0
 Factor:
 (W-180)(W-60)
 Solve for W
 Width=60 meters
 Length=180 meters