Let R be the statement : for all sets A, B and C, if A⊆B∪C and B ⊆C∪A then AΔB = C.

Question

Q: Is R true for all sets A, B and C? Prove answer

Let S be the statement: for all sets A, B, and C, if AΔB = AΔC then B⊆C.
Q: Is S true? prove answer

Thanks for your help.