If points X and Y are equidistant from point Z then d(X, Z) = d(Y, Z).
In the given question point B is 2 so d(A, B) = 2 - 0 = 2 and d(C, B) = 4 - 2 = 2
∴ d(A, B) = d(B, C)
Hence, points A and C are equidistant from point B
Point B is 2 so d(P, B) = 2 - (-2) = 4 and d(D, B) = 6 - 2 = 4
∴ d(P, B) = d(D, B)
Hence, points P and D are also equidistant from point B.
Therefore the set of points that are equidistant from point B are:
i) Points A and C
ii) Points P and D