Question

If $A=\{3,6,9,12,15,18\},B=\{4,8,12,16,20\},C=\{2,4,6,8,10,12\}$ and $D=\{5,10,15,20,25\},$ find
(i) $A-B$
(ii) $B-C$
(iii) $C-D$
(iv) $D-A$
(v) $n(A-C)$

Answer 1

$A=\{3,6,9,12,15,18\}$

$B=\{4,8,12,16,20\}$

$C=\{2,4,6,8,10,12\}$

$D=\{5,10,15,20,25\}$

$\left(1\right)A-B=\{3,6,9,15,18\}$

$\left(2\right)B-C=\{16,20\}$

$\left(3\right)C-D=\{2,4,6,8,12\}$

$\left(4\right)D-A=\{5,10,20,25\}$

$n(A-C)=4$