$$
\begin{array}{rl}
5 \cdot f(2x - 3) -4 & = 5 \left( (2x-3)^2 + 5(2x-3) \right) - 4 \\
& = 5 \left( 4x^2 - 12x + 9 + 10x - 15 \right) - 4 \\
& = 5 \left( 4x^2 - 2x - 6 \right) - 4 \\
& = 20x^2 - 10x - 30 - 4 \\
& = 20x^2 - 10x - 34 \\
\end{array}
$$