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8y-3(2y-3)=7y-2(5y+8)
8y- 3*2y -3*(-3) = 7y -2*5y -2*8
8y -6y  +9 = 7y -10y - 16
2y + 9 = -3y - 16
2y + 3y = - 16 - 9
5y = -25
y= -25 : 5
y= - 5
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8*(-5) - 3(2*(-5)-3) = 7*(-5)-2(5*(-5) +8)
-40 -3*(-10-3) = -35 -2(-25+8)
-40 - 3 *(-13) = -35 -2*(-17)
-40 +39 = -35 +34
-1=-1

2)
5(2y-9)+6y=4(3y-2)-21
10y - 45 + 6y = 12y -8 -21
16y-45= 12y -29
16y -12y = -29 +45
4y = 16
y=16:4
y=4
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5(2*4-9)+6*4=4(3*4-2)-21
5*(-1) +24 = 4*10 -21
-5 +24 = 40-21
19=19

3)
5y +7(3-y)=3(5-2y)-6
5y +21 -7y= 15-6y-6
-2y +21 = -6y +9
-2y+6y= 9-21
4y=-12
y=-12:4
у=-3
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5*(-3) +7(3- (-3) ) = 3(5-2*(-3)) -6
-15  + 7(3+3) = 3(5 + 6) -6
-15 +7*6 = 3*11 -6
-15 +42 = 33 -6
27=27

4)
7y - 4(3y+5)=2-3(4y-9)
7y - 12y -20 = 2 -12y +27
-5y -20 = -12y +29
-5y +12y = 29+20
7y= 49
y=49:7
у=7
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7*7 -4(3*7 +5) = 2- 3(4*7-9)
49 - 4*26 = 2 - 3*19
49 - 104 = 2-57
- (104-49) = -(57-2)
-55 = -55