1)5b+28=4b+21
5b-4b=21-28
b=-7
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2)4(2-0,5a)=-2(4+2a)
8-2a=-8-4a
-2a+4a=-8-8
2a=-16
a=-8
3)3y-22=8y+28
3y-8y=28+22
-5y=50
y=-10
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4)1+5(1,5-1,4x)=5-7,5x
1+7,5-7x=5-7,5x
8,5-7x=5-7,5x
-7x+7,5x=5-8,5
0,5x=-3,5
5x=-35
x=-7
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