\(3\cdot\left[\left(4-x\right)3+51\right]\div3-2^2=14\)
\(\Rightarrow3\cdot\left(12-3x+51\right)\div3-4=14\)
\(\Rightarrow3\cdot\left(-3x+12+51\right)\div3=14+4\)
\(\Rightarrow3\cdot\left(-3x+63\right)\div3=18\)
\(\Rightarrow-9x+189=18\cdot3\)
\(\Rightarrow-9x+189=54\)
\(\Rightarrow-9x=54-189\)
\(\Rightarrow-9x=-135\)
\(\Rightarrow x=15\)
3.( (4-\(x\)).3 + 51) : 3 - 22 = 14
(3:3).( (4- \(x\)).3 + 51) - 4 = 14
(4- \(x\)).3 + 51 = 14 + 4
( 4 - \(x\)).3 + 51 = 18
( 4 - \(x\)). 3 = 18 - 51
( 4 - \(x\)).3 = - 33
4 - \(x\) = - 33 : 3
4 - \(x\) = -11
\(x\) = 4 - (-11)
\(x\) = 15