We already have all the key information to solve this problem. We know that 9% tax was added to the original 100% price of the book of the book before taxes (the net price) so we know that the final selling price of $158.60 was 109% of the net price .
If we divide the final price (the gross price including taxes) by 109, we will find out what 1% of the pre-tax price was. If we multiply this answer by 100, we will know the full net price before tax.

Positive: 100 %

Answer #2 | 14/01 2014 13:15

You need a clearer statement of the problem to be solved. Are you trying to help the bookstore deal with student complaints about prices or are you are trying to help the student find more affordable text books? On whose behalf are you working, and what is your objective? Soaring text book prices is a big problem for students, especially pre-med, but it's not one that is easily solved.

Answer #1| 14/01 2014 10:18100 %