Answer:
0.8r
Step-by-step explanation:
r - 0.2r
= 1r - 0.2r ← factor out r from each term
= r(1 - 0.2)
= r × 0.8
= 0.8r
Looks like all you have to do it multiply the numbers together; there is no application of the Distributive Property to these problems.
The length of material needed for the border is the perimeter of the backyard play area
<h3>How to calculate the
length of
material needed </h3>
The area of the play area is given as:

The area of a trapezoid is calculated using:

Where L1 and L2, are the parallel sides of the trapezoid and H represents the height.
The given parameter is not enough to solve the length of material needed.
So, we make use of the following assumed values.
Assume that the parallel sides are: 25 feet and 31 feet long, respectively.
While the other sides are 10.2 feet and 8.2 feet
The length of material needed would be the sum of the above lengths.
So, we have:


Using the assumed values, the length of material needed for the border is 74.4 feet
Read more about perimeters at:
brainly.com/question/17297081
Is there anything else? Like what is the question asking?
<h3>
Answer: 297 square cm</h3>
=============================================
Work Shown:
Break up the figure as shown in the diagram below.
A rectangle and trapezoid form
-------------
Area of rectangle = base*height = 9*15 = 135 cm^2
Area of trapezoid = (1/2)*(b1+b2)*h = (1/2)*(18+9)*12 = 162 cm^2
total area = (area of rectangle)+(area of trapezoid)
total area = (135) + (162)
total area = 297 square cm