Given that f(x) = x^{2}-2x+5 and g(x) =x-18, what is the value of f(g(5)) -g(f(5))?
f(5) = 5^2 -2(5)+5 = 20
g(5) = -13
g(f(5)) = g(20) = 2 f(g(5)) = -13^2 -2(-13)+5 = 200
200-2 = 198
+36916 
