Beth subscribes to an online company that allows her to download electronic books. Her subscription costs a flat fee of $30 for up to 10 downloads each month. For each download over 10, there is an additional charge per download.
-- During the month of September , Beth downloaded 22 books and was charged $75. How much does each additional download cost ?

Question

Beth subscribes to an online company that allows her to download electronic books. Her subscription costs a flat fee of $30 for up to 10 downloads each month. For each download over 10, there is an additional charge per download. 
-- During the month of September , Beth downloaded 22 books and was charged $75. How much does each additional download cost ?

anonymous · Answer

We already know the first 10 books cost 30 dollars so we can remove this amount from both values

anonymous · Answer

So would we divide $75 by 22 ?

anonymous · Answer

no, you have to adjust these numbers for the first ten books which cost 30 dollars.

anonymous · Answer

We can adjust this by splitting the # of books and the cost into two groups

anonymous · Answer

First ten books
10 books = 30 dollars

The last twelve books
(22-10)*unknown=(75-30)