Hello - can anyone help explain some DS questions from my GMATPrep exam?

1) Are positive integers p and q both greater than n?

1) p - q is greater than n
2) q > p

Answer is C (both sufficient)

2) Juan bought some paperback books that cost $8 each and some hardcover books that cost $25 each. If Juan bought more than 10 paperback books, how many hardcover books did he guy?

1) The total cost of the hardcover books that Juan bought was at least $150
2) The total cost of all the books that Juan bought was less than $260

Answer is C (both sufficient)

3) All the clients that Company X had at the beginning of last year remained with the company for the whole year. If Company X acquired new clients during the year, what was the ratio of the number of clients that Company X had at the end of last year to the number of clients it had at the beginning of last year?

1) The ratio of the number of clients that Company X had at the beginning of last year to the number of new clients that it acquired during the year was 12 to 1.
2) Company X had 144 clients at the beginning of last year.

Answer is A (statement 1 is sufficient)