let f(x)=7x+4 and g(x)= 3x-9

g(f(x))

To find g(f(x)), we need to substitute the expression f(x) into the function g(x). Here's how to do it step by step:

1. Start with the function g(x) = 3x - 9.
2. Replace x with the expression f(x) = 7x + 4.
3. Substitute the expression, so we get g(f(x)) = 3(f(x)) - 9.
4. Now, let's substitute f(x) into g(x): g(f(x)) = 3(7x + 4) - 9.

To simplify further, we will distribute the 3 to both terms inside the parentheses:

g(f(x)) = 21x + 12 - 9.

Simplifying further, we combine like terms:

g(f(x)) = 21x + 3.

So, g(f(x)) simplifies to 21x + 3.