Answer:
f(-4) is basically just saying that you need to use the function given while x = -4.
The function given:
f(x) = -8(5-x)
We see that f(-4) means that x has to be -4, so we can substitute it in:
f(-4) = -8(5-(-4))
f(-4) = -8(9)
f(-4) = -72
Therefore, f(-4) is -72.