Answer:
tax: $18.9
total cost: $333.9
Step-by-step explanation:
$315 × 0.06 = 18.9
18.9 + 315 = 333.9
btw you can also do "315 × 1.06" to get the total cost without having to manually add the tax
add 4n and 5n, which is 9. 9n=-9, and if u divide both sides by nine, n=-1
Answer:
Widgets should be sold by $38.88 to maximize the profit.
Step-by-step explanation:
Vertex of a quadratic function:
Suppose we have a quadratic function in the following format:

It's vertex is the point 
In which


Where

If a<0, the vertex is a maximum point, that is, the maximum value happens at
, and it's value is
.
In this question:
The profit is given by:

Which is a quadratic function with 
The maximum profit happens at the x of the vertex. Thus

Widgets should be sold by $38.88 to maximize the profit.
That's 6! (factorial). It's 720.