A symmetrical form of the line of intersection of the planes x=ay+b and z=cy+d is :
x−ba=y−11=z−dc
x−b−aa=y−11=z−d−cc
x−ab=y−01=z−cd
x−b−ab=y−10=z−d−cd
x−ay−b=0 ....(1)
⇒y=x−ba
−cy+z−d=0 ....(2)
Solving (1) and (2), we get
cx=az−ad+bc .
⇒x=az−ad+bcc
So, x−ba=y1=z−dc