Answer: Divide the sale price by the percentage amount that was paid.
Step-by-step explanation:
If a book is on sale for $6.30 with a 30% discount it means that you paid 70% of the original cost. In order to determine what the original cost was you can divide the sale price by the percentage that was paid:
$6.30 / .7 = $9.00, which is the original price of the book.
You can then double check your work - $9 x 70% = $6.30.
