Total balls: 6 + 4 + 3 = 13
First pick green = total green / total balls = 4/13
adter picking the first ball there are 12 balls left.
Picking red = total red/ total balls left = 6/12 = 1/2
probability of picking both = 4/13 x 1/2 = 4/26 = 2/13
answer: 2/13