To determine the value of [tex]\( f(x) \)[/tex] when [tex]\( x = -5 \)[/tex] in the function [tex]\( f(x) = 5x + 40 \)[/tex], follow these steps:
1. Substitute the value of [tex]\( x \)[/tex] into the function.
[tex]\[
f(-5) = 5(-5) + 40
\][/tex]
2. Perform the multiplication inside the function.
[tex]\[
5 \times -5 = -25
\][/tex]
3. Add the product to 40.
[tex]\[
-25 + 40 = 15
\][/tex]
Therefore, [tex]\( f(-5) = 15 \)[/tex].
Hence, the correct answer is [tex]\( \boxed{15} \)[/tex].
