List the elements of the following sets:

Question

(1) {factor of 24}.
(2) {Negative integers greater than _9}.
(3) {Integers whose squares are less than 200 but greater than 40}.
(4) {Odd positive numbers less than 30}.

(Q2) Given that Y={multiples of 3 less than 20}, find the number of proper subsets of Y?

Answer 1

Q2: There are 6 members in Y: 3,6,9,12,15,18, so there are 2^6-2 = 62 proper subsets

surely you can handle the other items ...
#3 starts with
7^2 = 49
8^2 = 64
...
14^2 = 196