SOLUTION
Given the question in the question tab, the following are the solution steps to get the answer
Step 1: State the formula for the price of the book after discount is removed

Step 2: Calculate the new price of the book at store A after the discount

Step 3: Calculate the new price of the book at store B after the discount

Step 4: Compare the prices at the two stores to get the store that sells the book at lower price sale
Hence, it can be seen from the calculations above that Store A's sale price is $21.24, and Store B's sale price is $20.99 which is Option C.