Answer:
Between 1000 and 5000 snowboards will make the function AP(x) >0.
Step-by-step explanation:
Since x can only take possitive values, we have that AP(x) = P(x)/x > 0 if and only if P(x) > 0.
In order to find when P(x) > 0, we find the values from where it is 0 and then we use the Bolzano Theorem. 
P(x) = R(x) - C(x) = -x²+10x - (4x+5) = -x²+6x - 5. the roots of P can be found using the quadratic formula:

Therefore, P(1) = P(5) = 0. Lets find intermediate values to apply Bolzano Theorem:
- P(0) = -5 < 0 ( P is negative in (-∞ , 1) )
- P(2) = -4+6*2-5 = 3 > 0 (P is positive in (1,5) )
- P(6) = -36+36-5 = -5 < 0 (P is negative in (5, +∞) )
The production levels that make AP(x) >0 are between 1000 and 5000 snowboards (because we take x by thousands)
 
        
             
        
        
        
For
|a|<b
assume
-b<a<b 
so
add 5 to both side
|-2-8x|<66
assume
-66<-2-8x<66
add 2 to both sides
-64<-8x<68
divide everyboy by -8, don't forget to flip sign
8>x>-8.5
-8.5<x<8
the solution is all numbers between -8.5 and 8, not including -8.5 and 8
in interval notation: (-8.5,8)
or
S={x|-8.5<x<8}
        
             
        
        
        
The answer is exponential decay
        
             
        
        
        
200-50= 150
So you need to get 150 dollars in a month. If you get 20 dollars a week, then 150/20 will give you 7.5. So it will take you 7.5 weeks to get 150 dollars