The first derivative (Business Mathematics)

The first derivative of f(x)=\frac{6-4x}{x-4} is…
a. \frac{10}{x^2-8x+16}
b. -\frac{10}{x^2-8x+16}
c. \frac{10}{x-4}
d. \frac{22-8x}{x^2-8x+16}
e. 22-8x