The given masses are ,

the coordinates are .

The moment of the x - axis is:

            (Substitute)

                            (Multiply)

                                      (Add)

The moment of the y - axis is:

              (Substitute)

                              (Multiply)

                                        (Add)

The sum of the masses is:

                                      (Substitute)

                                             (Add)

Therefore center of the mass is:

                              (Center of the mass)

                               (Substitute)

                                    (Simplify)

The center of the mass of the given system of points is .