What am I doing wrong?
Use f(x)=2x-3 and g(x)=1-x2 to evaluate the expression.
G(f(4))
=1(2x-3)-x2
=(2x-3)-x2
=(2(4)-3)-(4)2
=(8-3)-16
=5-16
=-11
the answer is suppose to be -24

First the notation "x2" I believe is supposed to mean x^2 ("x squared"), not two times x.

Starting with g(x) = 1 - x^2, you can substitute f(x) for x into g(x):

g(f(x)) = 1 - [f(x)]^2

Since f(x) = 2x-3, then:

g(f(x)) = 1 - (2x-3)^2

For x = 4, you have:

G(f(4)) = 1 - (2(4)-3)^2 = 1 - (-5)^2 = -24