12 - 60*x -------------- 2 5*c + 4*c - 1
(12.0 - 60.0*x)/(-1.0 + 4.0*c + 5.0*c^2)
12*(1 - 5*x) ---------------- -1 + c*(4 + 5*c)
-(-12 + 60*x) --------------- 2 -1 + 4*c + 5*c
-12*(-1 + 5*x) ------------------ (1 + c)*(-1 + 5*c)