We are given the function $f(x) = 23.2x + 2.5$ and need to find its value at $x = -4.2$.

Step-by-step Solution:

1. Substitute $x = -4.2$ into the function:

$f(-4.2) = 23.2(-4.2) + 2.5$

2. Multiply $23.2 \times (-4.2)$:

$23.2 \times (-4.2) = -97.44$

3. Add $2.5$ to $-97.44$:

$f(-4.2) = -97.44 + 2.5 = -94.94$

Final Answer:

The value of $f(-4.2)$ is $-94.94$, so the correct answer is (b) -94.94.

Would you like further clarification, or have any questions on this?

Here are some related questions:

1. What is the slope of the function $f(x) = 23.2x + 2.5$?
2. How does changing the value of $x$ affect the value of $f(x)$?
3. What is the y-intercept of the function $f(x) = 23.2x + 2.5$?
4. If $x = 0$, what is the value of $f(x)$?
5. How would the function change if the slope was halved?

Tip: Always start by substituting values carefully into the equation, and perform each operation step by step to avoid calculation errors.