4a x+70=-100, x=-170
4b y+8=2000, y=2008
4c z+29=-718, z=-747
5a 3x=81, x=81:3= 27
5b -11y=121, y= -11
5c -35z=-210, z=6
6a x:(-8)=-20, x=(-8)(-20)=160
6b y:38=10, y=380
6c z:(-19)=-18, z=342
7a 3x+72=0, 3x=-72, x=-24
7b -8y+800=0, -8y=-800, y=100
7c 22z+440=0, 22z=-440, z=-20
