The total amount of beads is 8+4 = 12. 8 of these are black beads, so that is what we want, so 8/12 or 2/3. For the second one, one black bead is already taken so 8-1 = 7 are left and for the total 12 - 1 = 11 are left, so 7/11. Multiply this by 2/3 and we get 14/33.
