Answer:
20%
Step-by-step explanation:
Let's say that the 10 items cost $1 each. That would mean you spend $10.
As of that, the cost of 8 items (selling price) is also $10, meaning that you would spend $1.20 to buy the item
($1.20 - $1)/($1) = .20/1 = 1/5 = 20%
