Customer: “I thought that your tacos were 79 cents today.”

Me: “Yes, ma’am, they are. If you’ll look at the bottom of your receipt, it’ll show you that the price was discounted.”

Customer: “But it says $1.09 here, not 70 cents. You did this wrong.”

Me: “Ma’am, if you’ll notice the bottom of the receipt, it has a negative amount. That means that much was taken off of the price of tacos.”

(The customer looks lower on the receipt and becomes indignant.)

Customer: “What? I don’t owe you 90 cents!”

Me: “No, ma’am, you don’t. That just says that’s how much was taken off the tacos to make them 79 cents.”

Customer: “But you charged me $1.09. It clearly says that your tacos today are 79 cents.”

Me: “Ma’am, can I see your receipt?”

(I take the receipt, and use a pen to mark out the price and put in $0.79 on it.)

Customer: “Oh! That looks better. Thanks so much.”

(She happily takes her food and leaves.)