We have been given that c = 5 and d = 4
We will have to substitute these values of c and d into the expression given
Upon substitution
[tex]\begin{gathered} 6(5)^2\text{ - 5(4) + 8} \\ 6\text{ x 25 - 20 + 8} \end{gathered}[/tex][tex]\begin{gathered} 150\text{ - 20 + 8} \\ \\ 130+8 \\ \\ \Rightarrow\text{ 138} \end{gathered}[/tex]