Answer:
550
Step-by-step explanation:
 
        
                    
             
        
        
        
Whenever you face the problem that deals with maxima or minima you should keep in mind that minima/maxima of a function is always a point where it's derivative is equal to zero.
To solve your problem we first need to find an equation of net benefits. Net benefits are expressed as a difference between total benefits and total cost. We can denote this function with B(y).
B(y)=b-c
B(y)=100y-18y²
Now that we have a net benefits function we need find it's derivate with respect to y.

Now we must find at which point this function is equal to zero.
0=100-36y
36y=100
y=2.8
Now that we know at which point our function reaches maxima we just plug that number back into our equation for net benefits and we get our answer.
B(2.8)=100(2.8)-18(2.8)²=138.88≈139.
One thing that always helps is to have your function graphed. It will give you a good insight into how your function behaves and allow you to identify minima/maxima points.
 
        
             
        
        
        
Answer:
3/-1
Step-by-step explanation:
The slope is 3/-1 (Rise 3 on the y axis, run to the negatives by 1 on the x axis)
To find the slope of two points, use the formula of y2-y1/x2-x1 (For example, with this equation it would be 10-4/10-12)
I'm not sure what it means to interpret the slope, but hopefully this helped you!
 
        
             
        
        
        
Answer:
<em>A)0.09x</em>
Step-by-step explanation:
The original price of the bicycle is x.
The discounted price of the bicycle is x - 30. It is a $30 discount.
The tax goes on the original price. 0.09x is the 9% tax applied to the original price x.
Answer: 0.09x
 
        
                    
             
        
        
        
$2.99 + 7% of $2.99 =
= $2.99 + 7% * $2.99
= $2.99 + 0.07 * $2.99
= $2.99 + $0.21
= $3.20