Let's first find $(f + g)(x)$ using the given functions:

• $f(x) = 3x^2 + 3x - 18$
• $g(x) = x - 2$

The sum of the functions is:

$(f + g)(x) = f(x) + g(x) = (3x^2 + 3x - 18) + (x - 2)$

Now, let's combine like terms:

$(f + g)(x) = 3x^2 + 3x + x - 18 - 2$

$(f + g)(x) = 3x^2 + 4x - 20$

Therefore, the answer is:

$(f + g)(x) = 3x^2 + 4x - 20$

Would you like to explore the other parts of the question, such as $f - g$, $fg$, or $\frac{f}{g}$, or their domains?

Here are five related questions for you to consider:

1. What is $(f - g)(x)$ for the given functions?
2. How do we find $(fg)(x)$, the product of the two functions?
3. What are the restrictions on the domain when calculating $\frac{f}{g}(x)$?
4. How do you determine the domain of a sum of functions like $f + g$?
5. Can you solve $f(x) = g(x)$ to find where the two functions intersect?

Tip: When adding or subtracting functions, always combine like terms carefully to simplify the expression.