Answer:
The walk will cost $8164.
Step-by-step explanation:
Given:
Diameter of the circular pond (D) = 24 yd
Width of the gravel path (x) = 2 yd
Cost per yard of the path = $50
Now, radius of the circular pond is half of the diameter and is given as:

Now, area of the pond is given as:

Area of the complete path including the pond area is given as:

Now, area of the gravel path can be obtained by subtracting the pond area from the total outer area. This gives,

Now, using unitary method,
Cost of 1 square yard of path = $50
∴ Cost of 163.28 square yard of path = 50 × 163.28 = $8164
Hence, the walk will cost $8164.
ABC ~ A’B’C’
So, AB=A’B’ , BC=B’C’ , AC = A’C’
Given, AB=15 and A’C’=4
So, AC = 4 , A’B’ = 15
So basically you use the ratio they have given you. You either multiply by 2 if image is enlarged or divide by 2 if it is reduced. (Keep in mind I got the 2 from your ratio : 1inch : 2inches) Therefore the find the original width, you multiply 10 by 2, giving you 20 inches.