Each of three sets A,B,C has exactly 3 elements. A−B={1,5}; B−C={2,4}; C−A={3,7}. Find A,B and C.

Answer 1

A-B = {1,5} so A = {1,5,a}
B-C = {2,4} so B = {2,4,b}
C-A = {3,7} so C = {3,7,c}
a,b,c could be almost anything. But some possibilities are
A = {1,2,5}
B = {2,3,4}
C = {1,3,7}