Answer:
at 
Step-by-step explanation:
Given: The length of the rectangle is
and width of the rectangle is 
To find: An expression that can be used to find the perimeter of the rectangle, and the perimeter when x is 4.
Solution:
Here, Length is given as
width of the rectangle is 
Let P represents the perimeter of the rectangle
We know that perimeter of a rectangle is 
So, we have



Therefore, the expression to find the perimeter is 
Now, we need to find the perimeter at
On substituting
in
we have,




Hence, the perimeter is 62 units when x is 4.