Let $A=\{1,2,\{3,4\}, 5\} .$ Which of the following statements are incorrect and why ?
$1 \subset A$
Examine whether the following statements are true or false :
$\{ a,b\} \not\subset \{ b,c,a\} $
Write the following sets in the set-builder form :
$\{ 3,6,9,12\}$
In the following state whether $\mathrm{A = B}$ or not :
$A = \{ x:x$ is a multiple of $10\} ;B = \{ 10,15,20,25,30 \ldots \ldots \} $
Show that the set of letters needed to spell $"\mathrm{CATARACT}"$ and the set of letters needed to spell $"\mathrm{TRACT}"$ are equal.