F(x) = -x^2 – 10x + 16
Find f(-7)

The answer is F(-7) = 37

f(- 7) = 37

Step-by-step explanation:

To evaluate f(- 7), substitute x = - 7 into f(x), that is

f(- 7) = - (- 7)² - 10(- 7) + 16 = - 49 + 70 + 16 = 37

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.