$-2\le x\le 4\Rightarrow -8\le 4x\le 16\Rightarrow -6\le 4x+2\le 18\Rightarrow {{D}_{f\left( x \right)}}=\left[ -6,18 \right]$  $-6\le \frac{x}{3}\le 18\Rightarrow -18\le x\le 54\Rightarrow {{D}_{f\left( \frac{x}{3} \right)}}=\left[ -18,54 \right]\Rightarrow {{D}_{-f\left( \frac{x}{3} \right)+1}}=\left[ -18,54 \right]$