Final answer:
To find f(-6) for the function f(x) = 4.5x + 9, you substitute -6 for x and calculate, resulting in f(-6) being -18.
Step-by-step explanation:
If f(x) = 4.5x + 9, then to find f(-6), we simply replace the variable x with -6 in the function and calculate the result.
f(-6) = 4.5(-6) + 9
= -27 + 9
= -18
Thus, the value of f(-6) is -18.