Let the point O be the origin that is, O =(0,0), A = (1,0)
so,B = (0.5, 0.866)
[As OAB is an equilateral triangle]
X-coordinate of the center of mass, X = (0*3 + 1*4 + 0.5*5)/(5+4+3)
= 6.5/12 = 0.54 m
Y- Coordinate of the center of mass, Y = 0*3 + 0*4 + 0.866*5/12
= 0.36 m
Center of mass of the system, (X, Y) = (0.54m, 0.36m)