Let \(g(x)\) be a function piecewise defined as
\(g(x) = \left\{ \begin{array}{cl} -x & x\le 0, \\ 2x-41 & x>0. \end{array} \right.\)
If \(a\) is negative, find \(a\) so that \(g(g(g(10.5)))=g(g(g(a)))\).
The value of a is -6.
