posted by Kimberly .
I do not undeerstand this question for homework.
Determine if the set is closed for the given operation.
1. yes or no- The set of positive fractions for division.
2. yes or no=The set of positive integers for subtraction.
Can someone help me? Is there a website that I can go to to explain this to me. I have had someone send me to a help site before but cannot remember it.