A = {1, 3, 4, 6, 8, 10}, B = {3, 7, 8, 10}, C = {4, 8, 11}
A∪B = {1, 3, 4, 6, 7, 8, 10}
(A∪B) ∩ C = {1, 3, 4, 6, 7, 8, 10} ∩ {4, 8, 11} = {4, 8}
Ответ: {4, 8}