For this case we have the following two functions:
f(x)=3x^2+4x-3
g(x)=-2x-5
And we want to find g(f(x)) and we can do the following:
[tex]g(f(x))=-2(3x^2+4x-3)-5[/tex]And if we solve we got:
[tex]g(f(x))=-6x^2-8x+6-5[/tex][tex]g(f(x))=-6x^2-8x+1[/tex]