If the family ate 3/4 of the cake, or 3/4 of 8 equal parts, then the family ate 6 of the eight parts, or 3/4 (which should be no surprise).
3/4 of the 6 equal parts of the phone would be 18/6 of the pone, which boils down to 3 1/2 parts, which is the greatest number of parts of the pone that could have been eaten. Since the family ate more cake than phone, the appropriate answer here would be "just under 3 1/2 parts."
