TITLE: Would my method of solving this symmetric difference set be correct and is my answer correct?
QUESTION [1 upvotes]: Problem:  If A = {1, 2, 4, 6, 7} and B = {1, 2, 4, 6} and C = {1, 3, 4, 7}, what is A ⊕ B ⊕ C? 
1) A − B = {1, 2, 4, 6, 7} − {1, 2, 4, 6} = {1, 2, 4, 6, 7} − {1, 2, 4, 6} = {7}
2) B − A = {1, 2, 4, 6} − {1, 2, 4, 6, 7} = {1, 2, 4, 6} − {1, 2, 4, 6, 7} = {} 
3) A ⊕ B = (A − B) ∪ (B − A) = {7} ∪ {} ={7}
4) (A ⊕ B) − C = {7} − {1, 3, 4, 7} = {7} − {1, 3, 4, 7} = {}
5) C − (A ⊕ B) = {1, 3, 4, 7} − {7} = {1, 3, 4, 7} − {7}= {1, 3, 4}
6) (A ⊕ B) ⊕ C = ((A ⊕ B) − C) ∪ (C − (A ⊕ B)) = {} ∪ {1, 3, 4} = {1, 3, 4}

REPLY [2 votes]: Your answer and working appear to be correct. A noteowrthy fact: for a family of sets $A_1,\cdots,A_n$, we can show that
$$\bigoplus_{i=1}^n A_i = \{ \text{all elements belonging to an odd number of the } A_n \}$$
You can use this fact to quickly verify your answer in a case like this.
{"set_name": "stack_exchange", "score": 1, "question_id": 3589677}