Final answer:
The markdown on a single yogurt cup during the sale is $0.22, calculated by the difference between the regular price and the sale price.
Step-by-step explanation:
The original price of one yogurt cup is $0.55. During the sale, each yogurt cup effectively costs 3 for $1, which means each cup would be
ately $0.33 if you buy in multiples of three. To calculate the markdown on a single cup, subtract the sale price from the regular price: $0.55 - $0.33 = $0.22. Therefore, there is a $0.22 markdown on each yogurt cup when purchasing three for $1.