Answer:

Step-by-step explanation:
Given:
Mass of the first particle 
Mass of the second particle 
Mass of the third particle 
xy coordinate of the first particle 
xy coordinate of the second particle 
coordinate of the centre of mass of three-particle system 
We need to find the xy coordinate of the third particle.
Solution:
First we calculate total mass of the three-particle system.



x coordinate of the centre of mass of the three-particle system are given as;

Rewrite the equation for 

Part a.

Substitute all given values in above equation.


Part b.
Similarly for
coordinate.

Substitute all given values in above equation.


Therefore, xy coordinate of the third particle 