№80.
1) 3х = -6
х = (-6):3
х = -2
2) х+3 = 6
х = 6-3
х = 3
3) 4х-4 = х+5
4х-х = 5+4
3х = 9
х = 9:3
х = 3
4) 5х-8 = 2х+4
5х-2х = 4+8
3х = 12
х = 12:3
х = 4
№81.
1) х+5 = -6
х = - 6-5
х = -11
2) 4-х = -1
-х = -1-4
-х = -5
х = 5
3) 2х - 1 = 0
2х = 0+1
2х = 1
х = 1:2
х = 0.5
4) 3х+2 = 0
3х = 0-2
3х = -2
х = (-2):3
х = -2/3