To find $(f + g)(3)$, we need to first find the sum of $f(x)$ and $g(x)$, and then evaluate it at $x = 3$.

1. Add the two functions:

$(f + g)(x) = f(x) + g(x)$ Substituting the given functions:

$(f + g)(x) = (2x + 7) + (-3x - 1)$

Simplifying the expression:

$(f + g)(x) = 2x - 3x + 7 - 1 = -x + 6$

2. Now, substitute $x = 3$ into the expression for $(f + g)(x)$:

$(f + g)(3) = -(3) + 6 = -3 + 6 = 3$

So, $(f + g)(3) = 3$.

Would you like more details or have any questions?

Here are some related questions for further practice:

1. Find $(f - g)(3)$ for the same functions.
2. Solve for $(f \cdot g)(3)$.
3. Determine $\frac{f}{g}(3)$, if defined.
4. What is the domain of $(f + g)(x)$?
5. Evaluate $(f + g)(x)$ for $x = -2$.

Tip: When combining functions, always simplify the expression before substituting a specific value for $x$.