Answer
$$[x]_S=\left[ \begin {array}{ccc} 5\\ 4\\3\end {array} \right].$$
Work Step by Step
Since we have
$$x= 2(1,0,1)+3(1,1,0)+(0,1,1)=(5,4,3).$$
then we can write $x$ relative to the standard basis of $R^3$ as follows
$$x= (5,4,3)=5(1,0,0)+4(0,1,0)+3(0,0,1) .$$
Thus, he coordinates matrix of $x$ in $R^3$ relative to the
standard basis is
$$[x]_S=\left[ \begin {array}{ccc} 5\\ 4\\3\end {array} \right].$$
