An urn contains 8 red chips, 10 green chips, and 2 white chips. A chip is drawn and replaced, and then a second chip drawn. What is the probability of:

a) a white chip on the firs draw?

b) a white chip on the firs draw and a red chip on the second?

c) two green chips being drawn?

d) a red chip on the second, given that a white chip was drawn on the first?