Answer:
Area of rectangle =

Perimeter of rectangle =

Explanation:
We are given:
Length of rectangle = x
Width of rectangle = x-4
We are not given if we want to find area of rectangle or perimeter of rectangle.
So, I will be finding both
Area of rectangle
The formula used is:

Putting values and finding area

So, we get area of rectangle =

Perimeter of rectangle
The formula used is:

Putting values and finding perimeter

So, we get perimeter of rectangle =

I hope, it can help in solving the question.