[ QUOTE ]
4/40?
Why not 4/45 = 1/11.1?

I'm still trying to get better on my odds calling.

[/ QUOTE ]

Well:
1. He's using odds notation, and you're using probability notation, so
4:40 (note the use of a colon) is equivalent to 4/44.
2. He's put his opponent on the straight. With 8 cards accounted for that's 4 in 44 (or 4 to 40 odds) that the jack or four hits.