1,2x+1=1-x
0,8а+14=2-1,6а
12-(4х-18) =(36+4х) +(18-6х)
2х+5=2(х+1) +11

1,2x + 1 = 1 - x

2,2x + 1 = 1

2,2x = 0

x = 0

0,8a + 14 = 2 - 1,6a

2a + 14 = 2

2a = -12

a = -6

12 - (4x - 18) = (36 + 4x) + (18 - 6x)

12 - 4x + 18 = 36 + 4x + 18 - 6x

30 - 4x = 54 - 2x

30 = 54 + 2x

2x = -24

x = -12

2x + 5 = 2*(x + 1) + 11

2x + 5 = 2x + 2 + 11

2x + 5 = 2x + 13

5 = 13

x∈∅

решений нет