For b(i) all 500 people saw the advertisement in at least one magazine.

b(ii) You have to subtract out the 'and' numbers to get the numbers for X,Y,Z. Then add all of these up.

So magazine X: 180-84-52 - 38 = 6

magazine Y = 200-84-64 - 38 = 14

magazine Z = 192-52-64 - 38 = 38

6+14+38 = 58 from exactly 1 magazine