\(\left[3^4-\left(8^2+14\right):13\right]\cdot x=5^3+10^2\)
\(\Rightarrow\left[81-\left(64+14\right):13\right]\cdot x=125+100\)
\(\Rightarrow\left(81-78:13\right)\cdot x=225\)
\(\Rightarrow\left(81-6\right)\cdot x=225\)
\(\Rightarrow75\cdot x=225\)
\(\Rightarrow x=225:75\)
\(\Rightarrow x=3\)