\(4\cdot\left(5-x\right)-2^3=2^4\cdot3\)
\(\Rightarrow4\cdot\left(5-x\right)-2^3=16\cdot3\)
\(\Rightarrow4\cdot\left(5-x\right)-2^3=48\)
\(\Rightarrow4\cdot\left(5-x\right)=48+8\)
\(\Rightarrow4\cdot\left(5-x\right)=56\)
\(\Rightarrow5-x=56:4\)
\(\Rightarrow5-x=14\)
\(\Rightarrow x=5-14\)
\(\Rightarrow x=-9\)