The Investopedia article is correct.
Isn't your maximum profit when P≤77? Then you can exercise your 77P, but the call holder can't exercise his 97C. Your profit =77−P− options premiums.
You haven't accounted for the loss on the stock (Investopedia did). It is:
stock price + strike price - collar cost (-80 +77 -1.50)
Isn't your maximum loss when P≥97? ...