1) 5(х+7)-3(х-4)=8
2 )х-(3х-1)+12=4
3) -4/9х=20
4) 0,01х=-3

Пошаговое объяснение:

1)

5(х+7) - 3(х-4) = 8 ,

5х + 35 - 3х + 12 = 8,

5х - 3х = 8 - 12 - 35,

2х = -39,

х = -19,5   (или  х = -19 1/2),

2)

х - (3х-1) + 12 = 4 ,

х - 3х + 1 + 12 = 4,

х - 3х = 4 - 1 - 12,

-2х = -9,

х = 4,5   (или  х = 4 1/2),

3)

-4/9 х = 20,

х = 20 : (-4/9),

х = -20 * 9/4,

х = -45,

4)

0,01х = -3,

х = -3 : 0,01,

х = -3 : 1/100,

х = -3 * 100,

х = -300

1) 5(х+7)-3(х-4)=8; 5х+35-3х+12=8; 2х=-39; х=-19.5

2) х-(3х-1)+12=4; х-3х+1+12=4; -2х=-9; х=4.5

3) (-4/9)х=20; х=-20:(4/9)=-20*9/4=-45

4) 0,01х=-3; х=-3/0.0.; х=-300