Question

If $A=\{3,6,9,12,15,18,21\},B=\{4,8,12,16,20\},$

$C=\{2,4,6,8,10,12,14,16\},D=\{5,10,15,20\};$ find
(i) $A-B$

(ii) $A-C$

(iii) $A-D$

(iv) $B-A$

(v) $C-A$

(vi) $D-A$

(vii) $B-C$

(viii) $B-D$

(ix) $C-B$

(x) $D-B$

(xi) $C-D$

(xii) $D-C$

Answer 1

$A=\{3,6,9,12,15,18,21\}$
$B=\{4,8,12,16,20\}$
$C=\{2,4,6,8,10,12,14,16\}$
$D=\{5,10,15,20\}$
(i) $A-B=\{3,6,9,15,18,21\}$
(ii) $A-C=\{3,9,15,18,21\}$
(iii) $A-D=\{3,6,9,12,18,21\}$
(iv) $B-A=\{4,8,16,20\}$
(v) $C-A=\{2,4,8,10,14,16\}$
(vi) $D-A=\{5,10,20\}$
(vii) $B-C=\left\{20\right\}$
(viii) $B-D=\{4,8,12,16\}$
(ix) $C-B=\{2,6,10,14\}$
(x) $D-B=\{5,10,15\}$
(xi) $C-D=\{2,4,6,8,12,14,16\}$
(xii) $D-C=\{5,15,20\}$