To evaluate the function $b(x) = 7x - 4$ when $x = 8$, substitute 8 for $x$ in the equation:

$b(8) = 7(8) - 4$

Now calculate:

$b(8) = 56 - 4 = 52$

Thus, $b(8) = 52$.

Would you like further details or have any questions?

Here are 5 related questions you might find useful:

1. What is the value of $b(x)$ when $x = -3$?
2. How does the function change if the coefficient of $x$ is increased?
3. What is the slope of the function $b(x) = 7x - 4$?
4. Can you rewrite the function as $b(x) = mx + c$, and identify $m$ and $c$?
5. How would you graph the function $b(x)$?

Tip: When evaluating functions, always remember to carefully substitute values and simplify step-by-step for accuracy.