Are the following pair of sets equal ? Give reasons.

$A = \{ x:x$ is a letter in the word ${\rm{FOLLOW }}\} $

$B = \{ y:y$ is a letter in the word $WOLF\} $

Write down all the subsets of the following sets

$\{ a\} $

List all the elements of the following sers :

$E = \{ x:x$ is a month of a year not having $ 31 $ days ${\rm{ }}\} $

Write the following intervals in set-builder form :

$\left( {6,12} \right]$

In rule method the null set is represented by

State which of the following sets are finite or infinite :

$\{ x:x \in N$ and ${x^2} = 4\} $