Answer:
112 candies
Step-by-step explanation:
Start from the end.
Joe gave 25% of the remaining candies to his sister and has 21 candies left. Then
Write a proportion:
Joe gave 7 candies to his sister, so before this he had 21 + 7 = 28 candies.
He gave 4/6 of what he had left to his brother when he went home, so 2/6 of all his candies left ot him. Hence,
Write a proportion:
Joe gave 56 candies to his brother, so Joe had 28 + 56 = 84 candies when he went home.
Joe gave 1/4 of his total candies to his classmates, so 3/4 of his candies left to him. So,
Write a proportion:
Therefore, initially, Joe had 28 + 84 = 112 candies.