[tex](fg)(x)[/tex] is shorthand for [tex](f\times g)(x)=f(x)\times g(x)[/tex].
So if [tex]f(x)=x^2-4[/tex] and [tex]g(x)=3x+5[/tex], then
[tex](fg)(x)=f(x)\times g(x)=(x^2-4)(3x+5)=\cdots[/tex]
Finding the value of [tex](fg)(-1)[/tex] is just a matter of replacing [tex]x[/tex] with -1. We get
[tex](fg)(-1)=f(-1)\times g(-1)=((-1)^2-4)(3(-1)+5)=(1-4)(-3+5)=(-3)(-2)=6[/tex]
