A store sold a case for $17.85 that has been marked up 110%. What was the original price?

8.50

Step-by-step explanation:

Retail price = original price + markup

markup = original price * markup percent

Retail price = original price + original price * markup percent

Factor out the original price

Retail price = original price (1 + markup percent)

We know the retail price and the markup percent

17.85 = original price (1+110%)

Change to decimal form

17.85 = original price (1+1.10)

17.85 = original price (2.10)

Divide each side by 2.10

17.85/2.10 = original price * 2.10/2.10

8.50 = original price