Corectez: 5 a - 3 x ( b + c ) in loc de 3 b ( b + c ) !
3 a - 2 b = b - 2 a + 3 c
3 a + 2 a = 2 b + b + 3 c
5 a = 3 b + 3 c
5 a = 3 ( b + c )
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5 a - 3 x ( b + c ) + 145 : 5 - 8 = 21
= 3 x ( b + c ) - 3 x ( b + c ) + 29 - 8 =
= 0 + 21 =
= 21
