List all the elements of the following sers :

$A = \{ x:x$ is an odd natural number $\} $

Let $S=\{1,2,3, \ldots, 40)$ and let $A$ be a subset of $S$ such that no two elements in $A$ have their sum divisible by 5 . What is the maximum number of elements possible in $A$ ?

Consider the sets

$\phi, A=\{1,3\}, B=\{1,5,9\}, C=\{1,3,5,7,9\}$

Insert the symbol $\subset$ or $ \not\subset $ between each of the following pair of sets:

$\phi \,....\,B$

Write the following sets in roster form :

$A = \{ x:x$ is an integer and $ - 3 < x < 7\} $

What universal set $(s)$ would you propose for each of the following :

The set of isosceles triangles

Let $A=\{a, e, i, o, u\}$ and $B=\{a, i, u\} .$ Show that $A \cup B=A$