Here it is given that the width is x ft and total length of the fence is 2400 ft .
Let the length be y ft
So we have

Let A represents area, and area is the product of length and width .
So we get

Substituting the value of y, we will get

Second part
The area is maximum at the vertex, and vertex is

And

And that's the required dimensions .
They spent 5839 on electrical appliances and 6659 on furniture
The domain of G is 4 and the range of G is 9 (domain=x, range=y :))