Пошаговое объяснение:
a)
12х+3=16-х;
12x + x = 16 - 3
13x = 13
x = 13 : 13
x = 1
б)
3(х+2)=2(х-1);
3x + 6 = 2x - 2
3x - 2x = -2 - 6
x = -8
в)
4(0,4х-5)-3(0,2х+1)=-43.
1,6x - 20 - 0,6x - 3 = -43
x - 23 = -43
x = -43 + 23
x = -20