Question 894116
The difference quotient in calculus is defined as
[ f (x + h) – f(x) ] / h 
now we need to calculate f(x+h) given f(x) = 5-4x, therefore
f(x+h) = 5-4(x+h) = 5 -4x -4h
now for the difference quotient
(5 -4x -4h -5 +4x) / h = -4h/h = -4