For example, in the composition of(f g)(x) = f(g(x)), we need to replace each x found in f(x), the outside function, with g(x), the inside function. Step 3: Simplify the answer. Examples – Now let's use the steps shown above to work through some examples. Example 1: If f(x) = –4x + 9 and g(x) = 2x – 7, find(f g)(x).