400 meters of fencing. Twice as long as it is wide, what is the area

The area is 13,3 squared meters

Step-by-step explanation:

The 400 meters of fencing is the perimeter of the area. We know that:

perimeter = 2 (length + width)

or

P = 2 (l+w)

We also know that the length is twice the width, hence:

l = 2w

Substituting this information in the perimeter equation:

P = 2 (2w + w)

P = 4w+2w

P = 6w

w = P/6

Now, the area is defined as:

A = l*w

Therefore,

A = 2*w*w

A = 2 * w^2

Putting the w = P/6 in the previous equation

A = 2 * (P/6) ^2

A = 2 * P^2/36

A = P^2/12

And substituting the value of P and doing the math,

A = 13, 333 period 3 which we need to round to 13,3 which is the total number of significant digits given