Yes, she can, because if every person gets 15 cookies that's 75 cookies in total which means she will have 25 cookies leftover. Sophia could even give everyone 20 cookies but have no cookies leftover.
she has 17 slik roses already, and 6 friends give her 3 silk roses each, so that's 6 times 3, which makes 18, and 17 plus 18 is 35, so she has 35 silk roses in all.
