Chapter 3 - Solving Inequalities - 3-8 Unions and Intersections of Sets - Practice and Problem-Solving Exercises - Page 219: 35

$W ∩ X ∩ Z$ = {6}

We are asked to find the intersection of $W$, $X$, and $Z$. This means we find all elements that are common to $W$, $X$, and $Z$. $W$ and $X$ only have $6$ in common. The common element in these two sets is also an element in $Z$; therefore, all three sets have $6$. $W ∩ X ∩ Z$ = {6}