After Peter shared his fishballs equally with his 4 brothers, he was left with 7/12 of his fishballs. What fraction of his fishballs did each of his brother get?
The fraction he shared is total - amount left for himself = (1-7/12) = 5/12.
Each of the four recieved one quarter of that, which is 5/12 /4 = 5/48 of the his original number of fishballs.
