given f(x)=6(1-x), what is the value of f(-8)?
a) 54
b) 42
c) -8
d) -42

i need a proper answer with evidence, .

The answer would be D) -42. The question is asking for the value of the equation when x is equal to -8. Substitute -8 into any place x appears in the previous equation and solve. 
so, it would look like this: f(-8)=6(1-8)
1-8 = -7. 6(-7) = -42.

Idon’t know the answer to this