Let P = the price increase in dollars........and [revenue per ticket ] * [ number of purchasers] = total revenue....so
(20 + P)(800 - 30P) >= 12800 simplify
-30P^2 + 200P + 16000 >= 12800
Here's a graph of the optimal solution.....https://www.desmos.com/calculator/wjfwdtvwp8
The total revenue will be maximized when the ticket price is increased by about $3.33......and the max amount of revenue will be about $16,333
