Dados os conjuntos a={1,3,4,7,8},b={2,4,6,7},c={2,3,5, 7,8},qual e o conjunto (a u b)-c ?

(A U B) = {1,2,3,4,6,7,8}
{1,2,3,4,6,7,8} - {2,3,5,7,8} = {1,4,6}