Question

If universal set $\xi =\{a,b,c,d,e,f,g,h\},A=\{b,c,d,e,f\},B=\{a,b,c,g,h\}$ and $C=\{c,d,e,f,g\}$ find : $C-(B\cap A)$

Thus find the number of elements in the above set.

Answer 1

Intersection of two sets has the common elements of both the sets.
So, $B\cap A=$ { $b,c$ }
$C-(B\cap A)$ will have elements of C which are not in $(B\cap A)$
So, $C-(B\cap A)=$ { $d,e,f,g$ }

There are thus $4$ elements in the above set.