Items are sold for $45 each. 195 people are willing to buy them. For every $5 increase in price, 5 fewer people are willing to buy the item. Determine the maximum revenue and the number of price increases.

Let x be the number of increments.

Let y be the total cost.

$\displaystyle y=(195-5x)(45+5x)$

$\displaystyle y=-25x^2+750x+8775$

$\displaystyle y=-25(x^2-30x+225) (-225)(-25)+(8775)$

$\displaystyle y=-25(x-15)^2+14400$

Where total revenue = $14400

Where total numer of increases = 15