Answer:
Part 1)

Part 2)

Part 3)

Explanation:
Part 1) Find Pet exercise Area
we know that
The Pet exercise Area is equal to the area of a triangle
The area of a triangle is equal to

we have

substitute
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Part 2) Find Vegetable Garden Area (small rectangle):
we know that
The Vegetable Garden Area is equal to the area of a rectangle
The area of rectangle is equal to

we have

substitute
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Part 3) Find TOTAL Backyard Area (large rectangle)
we know that
The TOTAL Backyard Area is equal to the area of a rectangle
The area of rectangle is equal to

we have

substitute
