Set P consists of all the positive even integers less than 14,and set Q consists of all the positive

题目

Set P consists of all the positive even integers less than 14,and set Q consists of all the positive multiples of 3 less than 21.Set R consists of all members that are either in set P or set Q.How many members of set R are even?
(A) 6
(B) 7
(C) 9
(D) 10
(E) 12
我怎么觉得有18个 选哪个

答案

P={2,4,6,8,10,12}
Q={3,6,9,12,15,18}
R={2,3,4,6,8,9,10,12,15,18}
其中偶数个数是7,故选B