The number of octants in which both x-and y-coordinates are negative is

Three mutually perpendicular lines divide the whole space into 8 equal parts. Each part is called octant. The names of octants are OXYZ,OXYZ',OXY'Z,OX'YZ,OX'Y'Z,OX'YZ',OX'YZ',OX'Y'Z' The octants in which both x-and y-coordinates are negative are  OX'Y'Z,OX'Y'Z'