That's more difficult to answer since SBD is almost $10 now.. but I always calculate.
If a post has $10 in steemit then you have 10$-25% curation.
so you have $7,50 left. if you have 50/50 rewards.
You get 3,75 steem dollar which is now really $37,50 and you get 1 steem if steem price is $3,75. So all depends on the time when your post is made.
I hope this makes it a bit clear. or search some post on steemit which can explain it in more detail..
Actually that is not entirely correct: The witnesses have put the SBD | Steem ratio to ~ 75% | 25% to create a great market pressure. You can check the current average on http://steem.supply/
So we get more SBD than Steem.
This is incorrect. Look at my picture above. I got 48 SBD and 7.6 steem worth around 6.4 or so basically the same amount. i.e. 50:50 like @timcliff said.
This doesn't sound right.