Question 449748
A = {16, 18, 20, 22}


A' = {15, 17, 19, 21, 23, 24, 25} .... this is the set of U but excluding everything in A (ie it's everything but set A). So start with U, then delete every element found in A.



B = {17, 19, 20, 23, 24}


B' = {15, 16, 18, 21, 22, 25}




Now union A' and B' to get


A' U B' = {15, 16, 17, 18, 19, 21, 22, 23, 24, 25}



This is just the combination of the two sets (ie dump all the elements from both sets A' and B' into A' U B' and remove any duplicates).