\(10-4,7< a,2+a,2< 6+1,2\\ \left\{{}\begin{matrix}10-4,7< a,4\\a,4< 6+1,2\end{matrix}\right.\\ \Rightarrow\left\{{}\begin{matrix}a,4>5,3\\a,4< 7,2\end{matrix}\right.\\ \Rightarrow\left\{{}\begin{matrix}a>13,25\\a< 18\end{matrix}\right.\Rightarrow13,25< a< 18\)