1. Difficult exercise for me

Proved to mathematical relationships is true

I know it is silly but I need your help
and I want to summaries or exercises for this section (Logic Algebra and Sets)

2. This is an exercise in carefully following the definitions. Look in your book for the precise definitions of these operations, then write them out. For instance, on the first one, start with

$\displaystyle \{x\in \{y\in A\mid y\notin B\}\mid x\notin C\}$

and go from there.

3. Originally Posted by Tinyboss
This is an exercise in carefully following the definitions. Look in your book for the precise definitions of these operations, then write them out. For instance, on the first one, start with

$\displaystyle \{x\in \{y\in A\mid y\notin B\}\mid x\notin C\}$

and go from there.
thanx Tinyboss
but i dont understand how solve exercise for use this $\displaystyle \{x\in \{y\in A\mid y\notin B\}\mid x\notin C\}$
sorry but i haven't any exercise similar to the solution
I want a complete solution for one of these exercises plz
thanx again for u