There are 30 balls in a bag. 6 are red, 14 are blue, 3 are green and the remainder are yellow.
Two balls are to be picked out of the bag, without replacement. What is the probability of
picking:

a) 2 reds

b) a red and a yellow ball in any order
2 greens or 2 blues
d)
a red or blue followed by a green​