Final answer:
The statement is true for linear functions, but not in general for all functions.
Step-by-step explanation:
The statement is true if f(x) is a linear function.
However, it is not true in general for all functions, so the statement is false.
An example of a linear function where the statement is true would be f(x) = 2x.
If we substitute s + t into the function, we get f(s + t) = 2(s + t) = 2s + 2t.
On the other hand, if we substitute f(s) + f(t) into the function, we get f(s) + f(t) = 2s + 2t.
Therefore, the equality holds and the statement is true for linear functions.