There should be a typo in the question: the correct formula would be
[tex]X\cap(Y\cup Z)=(X\cap Y)\cup (X\cap Z)[/tex]
Let's compute [tex]X\cap (Y\cup Z)[/tex] first. We have
[tex](Y\cup Z)=\{1, 4, 5, 6, 7, 8, 9\}[/tex]
If we intersect this set with X, we have
[tex]X\cap (Y\cup Z) = \{5, 8, 9\}[/tex]
So, that would be the left hand side. For the right hand side, we have
[tex]X\cap Y = \{8\},\quad X\cap Z = \{5,9\}[/tex]
And their union is again [tex]\{5,8,9\}[/tex]