2 7/20+z=-4 11/15
z=-4 11/15-2 7/20=-(71/15+47/20)=
=-(71*4+47*3)/69=-(284+141)/60=-425/60=
=-7 5/60=-7 1/12
z=-7 1/12
2 7/20+z=-4 11/15
z=-4 11/15-2 7/20=-(71/15+47/20)=
=-(71*4+47*3)/69=-(284+141)/60=-425/60=
=-7 5/60=-7 1/12
z=-7 1/12