Answer :
[tex]\bf \begin{cases}
c(x)=4x-2\\\\
d(x)=x^2+5x
\end{cases}\qquad thus
\\\\\\
(c\circ d)(x)\implies
\begin{array}{llll}
c(x)=&4x-2\\\\
c[\ d(x)\ ]=&4(dx)-2\\\\
c[\ \boxed{x^2+5x}\ ]= &4(\boxed{x^2+5x})-2
\end{array} [/tex]
distribute and simplify
distribute and simplify