A regular octagon has 8 sides that are if equal length. Perimeter of any given octagon with side length, s, can be calculated using this equation that shows the relationship between its side lenght (s) and perimeter (P):
To complete the table, simply plug in the value of a in each case.
The answer would be (x,y) —> (x-1,y). the reasoning being that all of the points on the x axis move to the left by one unit, and all points on the y axis stay the same.