
Originally Posted by
survivorboi
UMMMM....let me guess. 13 students are married, and 21 students live with they parents. So...16 students aren't married (single) and don't live with parents? Guess...
Actually, as far as I understand it, you are going backwards.
It says "its knows that 3 of the married students live at their parents home."
I'm guessing that "knows" is supposed to be "known", in which case it would be 10 married, and 18 live with parents, but three of those 18 are ALSO 3 of the 10. So, add the 10 + 18, then minus three for the overlap, and you get 25.
Subtract
that from the total.