Answer :

6 2/3 is bigger because there are 3 pieces instead of 15
DISREGARD THE FIRST ANSWER THEY GOT IT WRONG 6 AND 12/15 IS LARGER IF WE CONVERTED BOTH TO IMPROPER FRACTIONS WE WOULD HAVE ( 6 and 2/3 = 100/15) and (6 and 12/15 = 102/15) SO ITS LARGER BY 2/15