Which could be the entire interval over which the function, f(x), is negative?

(–8, –2)
(–8, 0)
(–∞, –6)
(–∞, –4)

5y

step-by-step explanation:

1 and 0

step-by-step explanation:

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.