A = {0, 10, 20, 30, 40}
B = {10, 15, 20}
C = ∅
D = {10, 20}
A ∪ B = {0, 10, 15, 20, 30, 40}
A ∩ B = {10, 20}
A \ B = {0, 30, 40}
A ∪ C = {0, 10, 20, 30, 40}
B ∪ C = {10, 15, 20}