Let the number of fiction and non-fiction books in 2010 be represented by x and y, respectively.
From the first condition:
\(x+y=11500 ........... (1)\)
From the second condition:
\(1.1x+1.2y=11500............... (2)\)
Solving both equations, we find that \(x = 6000.\)
In 2015, the number of fiction books is given by \(1.1x=6600.\)