Question

решите уравнения : (z-2)+(z-1)+z=-3 ; 21+ (20-4x)-(11-2x)=0 ; 2u-3(7-2u)=3 ; 12-y =5(4-2y)+10 ; 2-2(x-8)=4x-4 
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Answer 1

z-2+z-1+z=-3
3z-3=-3
3z=0
z=0
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21+20-4x-11+2x=0
30-2x=0
-2x=30
x=15
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2u-21+6u=3
8u=24
u=3
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12-y=20-10y+10
-y+10y=20+10-12
9y=18
y=2
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Answer 2

-6x=-22

Answer 3

x=22/6

Answer 4

x=11/3

Answer 5

2u-21+6u=3
8u=24
u=8
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12-y=20-10y+10
12-y=30-10y
9y=18
y=2