These questions all require an answer of "yes", "no" or "cannot be determined", but all the answers turn out to be either "yes" or "cannot be determined". None of the answers is "no." Are there questions like this that ever yield a "no" answer? From the answer explanations, it seems unlikely "no" would be correct for any similar question.
In question 2, for example, the fact that 80 is a factor of r but we do not know the other factors of r mean that the ? in the factor tree could be anything. That means, based on the factor foundation rule, that it is always possible (though not definite) that 15 is a factor of r because all you have to do is replace the ? with a number that has 3 as a factor (which can be done simply by using 3 to replace the ?). Then r=3X80=240, which, as the explanation tells us, proves the answer is "cannot be determined".
Seems like you can just replace the unknown factor (?) with whatever missing factor is needed (3) to make the factor in question (15) work. So when would the answer be "no"?