If $aN = \{ax : x \in N\}$ and $bN \cap cN = dN$,where $b, c \in N$ are coprime numbers,then:

List all the elements of the following set:
$E = \{ x : x \text{ is a month of a year not having } 31 \text{ days} \}$

If $X = \{a, b, c, d\}$ and $Y = \{f, b, d, g\},$ find $X - Y$.

Let $A = \{1, 2, 3, 4, 5, 6\}$. Insert the appropriate symbol $\in$ or $\notin$ in the blank space:
$10 \dots A$

Make correct statements by filling in the symbols $\subset$ or $\not\subset$ in the blank spaces:
${ x:x \text{ is an equilateral triangle in a plane} } \dots { x:x \text{ is a triangle in the same plane} }$

Show that if $A \subset B$,then $(C - B) \subset (C - A)$.