B = event that the second ball is white

A = event that the first ball is white

P(A given B) = P (A | B) = P(A and B) divided by P(B).

P(A and B) = (5/9) (4/8) = 20/72 = 5/18

P(B) is the sum of the two outcomes:

Outcome 1: First ball is white, Second ball is white P= 5/18

Outcome 2: First ball is not white, second ball is white P = (4/9) (5/8) = 5/18

So P(B) = 5/18 + 5/18 = 10/18 = 5/9

Then P(A|B) = (5/18) divided by (5/9) which gives 1/2.

So there is a 50% chance that, given that the second ball is white, the first ball is white as well.

Good luck!