Pre-Calc Algebra

[eldarmasterjoe]

I understand for this question that it is asking for me to make an equation and solve for the vertex but I am having difficulty figuring out what the equation would be. Here is the question.

The manager of a 120-unit apartment complex is trying to decide what rent to charge. Experience has shown that at a rent of $1400, all the units will be full. On the average, one additional unit will remain vacant for each $20 increase in rent. What rent will maximize revenue?

 

[skeeter]

revenue = (rent price)(number of units occupied)

let x = number of $20 increases in rent

[math]r(x) = (1400+20x)(120-x)[/math]

 

[eldarmasterjoe]

Ah thank you! This helps a lot.