Answer:
Let d be the number of $2 decreases, and r be the company´s revenue, then the company can sell:
[tex]800+40d[/tex]
cellphones per week at a price of:
[tex]80-2d[/tex]
dollars.
Therefore, the quadratic equation that represents the revenue is:
[tex](800+40d)(80-2d)\text{.}[/tex]
Now, graphing the above equation we get:
From the above graph, we can determine the vertex and the vertex gives us for which value of d the company gets the maximum revenue.
The company should charge $80-10($2)=$80-$20=$60.
