2вариант даю 40балов

1)8x=100-20

8x=80

x=808

x=10

2)80-20-y=50

60-y=50

60-50=y

y=10

3)x-40=110-60

x-40=50

x=50+40

x=90

4)8x=380+20

8x=400

x=4008

x=50

5)x=70(-0.4)

x=-28

6)y=-6-8,1

y=-14,1

7)-4x=-7-13

-4x=-20

x=5

1) 4x+4x+20 = 100

20 + 8x = 100

8 x = 100-20

8 х = 80

х =80:8

х=10

2) 80-(20+у)=50

80-20-y = 50

60 - y = 50

-y = -10

y = -10 / (-1)

y = 10

3) (х-40)+60=110

x-40+60 = 110

20 + x = 110

x = 110-20

х = 90

4) 8х-20=380

8 x = 400

x = 400:8

x = 50

5) х:70=-0,4

х= -28

6) 8,1+у=-6

у= -6 -8,1

у= -14,1

7) 13-4х=-7

-4x = -20

x = -20 : (-4)

x = 5