I have been surrounded by credentialed ignoramuses

I bought a loaf of whole-wheat bread from the market; after the credit card transaction, I checked the receipt and saw the cashier had mistakenly charged me 45 TL—thinking it was sourdough—when it should have been 20 TL. She tried to calculate the refund amount but couldn't manage it, so she asked the girl next to her, "How much money do I need to give the customer?" The other girl replied, "If you subtract 20 from 45, you get 15." I burst out laughing, told them the correct figure, and got back 25 TL. I believe that even university graduates—and those with master's or doctoral degrees—often possess similar levels of culture and intelligence.