So I’ll do question 3. So normally you see f(x)= something plus x (something like that) you see it as a function of x.
So that notation of f(-1) means the function of -1. Which means you need to sub in -1 for x.
f(x)=-5x+5
f(-1)=-5(-1)+5
Negative times a negative is a positive
f(-1)=5+5
f(-1)=10