Let y=f(x) be a function with domain D = [-2, 6] and range R = [-4, 8]. Find the domain D and range R for each function. Assume f(2)= 8 and f(6)= -4.

(a) y= -2f(x)
(b)y= f(1/2)x
(c)y= f(x-3) + 1

please help, i am so confused! Its in the Graphs of Functions section in my Pre-calculus book.