2вариант даю 40балов
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
1)8x=100-20
8x=80
x=80÷8
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=400÷8
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