(1,5 điểm) Tìm x , biết: a) 18 − 2 x = 8 .b) 99 − ( 5 − 3 x ) = − 2. c) ( 454 − x ) + 4 3 = 116 .

a) \(18 - 2x = 8\)

\(2x = 18 - 8\)

\(2x = 10\)

\(x = 5\)

Vậy \(x = 5\).

b) \(99 - \left( {5 - 3x} \right) = - 2\)

\(5 - 3x = 99 - \left( { - 2} \right)\)

\(5 - 3x = 101\)

\(3x = 5 - 101\)

\(3x = - 96\)

\(x = - 32\)

Vậy \(x = - 32\).

c) \(\left( {454 - x} \right) + {4^3} = 116\)

\(\left( {454 - x} \right) + 64 = 116\)

\(454 - x = 52\)

\(x = 402\)

Vậy \(x = 402\).