Ответ: \[(a - 2)x = 9 + 3a\] \[(a - 2) \cdot 5 = 9 + 3a\] \[5a - 10 = 9 + 3a\] \[2a = 19\] \[a = 9,5\] \[Ответ:при\ a = 9,5.\]