A drug is injected into the bloodstream of a patient. The concentration of the drug in the bloodstream (in milligrams per cubic centimeter) $t$ hours after the injection is given by $$C(t) = \frac{0.13 t}{t^2 + 5}.$$ Find the instantaneous rate of change of the drug concentration with respect to time at the following times:

(A) $C'(.5)$ =

(B) $C'(3)$ =