Calculate the distance of center of mass of the following systems from point A in each system: 

1) System of two point masses of mass 1 kg and 4 kg separated by 8 meter. Point A is at point mass of 1 kg.  

2) System of horizontal and vertical rod of mass 6 kg and 8 kg and length 1 meter and 2 meter respectively. Point A is at mid of horizontal rod. 

3) System of two circular disks of radius 2 meter and 1 meter with equal density. Point A is the center of circular disk of radius 2 meter.