P(Winning) = 30/2000 = 3/200

P (against winning) = 1- 3/200 = 197/200

Odds against = number of losing tickets : number of winning (not total number) so 1970 : 30

Of 2000 raffle tickets, 1970 are not yours. So your odds of losing are 1970/2000 or 0.985.

1970:30 =

197:3