Ответ:

а)

\(98x - 87x = 594\)

\(11x = 594\)

\(x = 54\).

б)

\(23x - 12x + 6x + 5 = 90\)

\(17x + 5 = 90\)

\(17x = 85\)

\(x = 5\).

в)

\((16x - 10x + 3) \cdot 4 = 132\)

\((6x + 3) \cdot 4 = 132\)

\(6x + 3 = 33\)

\(6x = 30\)

\(x = 5\).

Ответ: а) \(x = 54\); б) \(x = 5\); в) \(x = 5\).