To find this information, you could try these resources:
* McDonald's Archives: They may have records of historical menu pricing.
* Inflation Calculators: Websites that track inflation can help you estimate the price of an item from the past.
* Historical Food Price Databases: Some online databases might hold records of food prices.
* Old Newspaper Articles: Look for articles from 1972 that mention McDonald's menu prices.
* Old McDonald's Menus: If you can find a menu from that period, it might have the answer.
Good luck with your search!