[FletchJr.]

Just as pudley4 posted:
The easiest way is to figure out the chance that he doesn't hit the flush, then subtract from 1 to find the chance he does.
The brackets are my added information so it is easier to understand)

"7 total cards known,(2 flush cards you hold, ace flush card the opponent holds, the other non flush card the opponent holds and the flop) 45 remaining (52 - 7 known). 6 flush cards known ( 3 on flop, 2 in your hand, and two 1 in opponents hand), 7 remaining.

Probability of not hitting on the turn= 38/45. (45 - 7 flush cards left)
Probability of not hitting on the river= 37/44. (44 - 7 flush cards left)

Multiply these together to get 1406/1980. (this is the chance of him not getting the flush)
(subtract from one gives you the opposite, so obviously the chance of him getting the flush)Subtract from 1 to get 574/1980=.28989.... So he has a 28.9898% chance of hitting the flush by the river.

To figure out the odds, it's 1406 to 574 (chances of him not getting the flush compared to him getting the flush) against him hitting=2.449 to 1 against.

Yet again thanks for the perfect post pud