If Dave has 15 dollars and must spend 8 dollars of it on a book, then he will have 7 dollars left. If he then buys two of the same cards for his friends, the most he will be able to spend is half of 7 dollars for each of them, which will be 3 dollars and 50 cents.
Answer:
Step-by-step explanation:

just to clarify the engineering notation, E6 is just 1 and 6 zeros, or a million, thus, 107,000,000 is just 107E6.