f(x) = If[0 < x < 1000, (-25 * x^(2)) + (32400 * x)]
g(x) = If[0 < x < 1000, (0.03 * x^(3)) - (48 * x^(2)) + (27600 * x)]
h(x) = f(x) - g(x)
A = Extremum(h)
B = Extremum(g)
C = Extremum(g)
D = Extremum(g)
E = Extremum(f)
F = Extremum(h)