There are \(70\) girls in a year group at a school. The Venn diagram gives some information about the numbers of these girls who play rounders \((R)\), hockey \((H)\) and netball \((N)\).

\(n(R)=28,\qquad n(H)=38,\qquad n(N)=35.\)

Find the value of \(x\) and hence the number of girls who play netball only.