Answer:
390=W 195=L Area=76050
Explanation:
You have two lengths and one width for your perimeter
P= 2L + W
you are given your perimiter 780
780= 2L + W
To solve for your maximum Width
780-2L=w
Area is L * W
A= (780-2L)*L
A= 780L - 2L^2
the derivitive of the Area
A' = 780-4L =0
add 4L to both sides
780=4L
divide by 4 on both sides
195=L
Bring back 780-2L=W and plug in what you now know is L
780-2(195)=W
780-390=W
390=W