A box contains 5 red, 3 black, and 2 white cubes. A cube is drawn randomly and has its color noted. The cube is then replaced, together with 2 more of the same color. A second cube is then drawn.
a) Find the probability that the first cube selected is red.
b) Find the probability that the second cube selected is black.
c) Given that the first cube selected is red, what is the probability that the second cube selected is black?