Answer:

Step-by-step explanation:
The missing details in the question are:


Required
The perimeter
This is calculated as:

So, we have:

Open bracket

Rewrite as:

Step-by-step explanation:
The area of a rectangle is 171 m²
Let l is the length and b is the width of the rectangle
It width is 10 m less than the length. So,
b = l-10 ...(1)
Area of a rectangle is given by :

or
l = 9 m or l = 19 m
If l = 9 m,
b = 9-10 = -1 m (can't be possible)
If l = 19 m
b = 19-10 = 9 m
So, the length an the breadth of the rectangle is 19 m and 9 m respectively.
All you have to do is solve for x. See the following steps below.
Step 1. Subtract

from both sides

Step 2. Simplify

to

Your Answer Will be 25 . All you do to find the mean is add all of the numbers together, then divide it by how many numbers you added . So in this case it was 5. Hope that helped!:)