Answer: 
Step-by-step explanation:
The missing figure is attached.
The perimeter of a rectangle is:

Where "l" is the lenght and "w" is the width.
You can identify in the figure that:

Then, knowing the perimeter of the rectangle, you can make the subsitution into the formula:

Now you must simplify and solve for "z"

Finally, substituting the value of "z" into
, you get:
