Answer:
The domain is the set of all the values of x, so it would be -3, -5, -6, -9, 0. The range would be every set of y, so it would be 7, -8, -1, -3. Finally, this relation is indeed a function.
Domain: -3, -5, -6, -9, 0
Range: 7, -8, -1, -3
Is it a function? Yes
Well actually depending on the size, if a small one I would use liters, but if a large ones like Olympics I would use kilolitres.
To find the length, divide the peremiter by 2 and then subtract the width.
Length= Peremiter/2 - width
L = P/2 - W
L = 168/2 - 36
L = 84 - 36
L = 48
The length is 48