C = A + B, C + A = B, C ∈ (A ∩ B), c = |a - b|, C + A =B, C - A - B, c/a+b, c = a + b, C−A−B, C. a : b ∈ ?;, C. a // b;, c = a // b, C. A∪B., c) A ∩ B = ∅., C. A = B, C. a // b., C. A + B