[list=1][*]Plot the planes with equations:[br][b]x−2y+4z=4[br]x+y−z=2[br]x+3y+z=6[/b][br][br][/*][*]Use the [b]Intersect two surfaces[/b] tool to find the lines of intersection of two of the pairs of planes.[br][br][/*][*]Use the [b]Intersect[/b] tool to find the point of intersection of these lines. [br][/*][/list]