4:
=>\(8\left[15x+11\right]=64\cdot31:2^2=16\cdot31\)
=>15x+11=2*31=62
=>15x=51
=>x=3,4
4: \(=\dfrac{\left(8^9\cdot13+8^8\cdot27\right)}{2^{26}\cdot5}=\dfrac{2^{27}\cdot13+2^{24}\cdot27}{2^{26}\cdot5}\)
\(=2\cdot\dfrac{13}{5}+\dfrac{1}{4}\cdot\dfrac{27}{5}=\dfrac{131}{20}\)