The vector position of a 3.45 g particle moving in the xy plane varies in time according to

1 = 3 + 3t + 2t2
where t is in seconds and is in centimeters. At the same time, the vector position of a 5.00 g particle varies as 2 = 3 − 2t2 − 6t.

Determine the vector position of the center of mass at t = 2.80.