considering what is written in white paper under a section of Sustainable Debt to Ownership Ratios says: "For every SMD Steem creates, $19.00 of STEEM is also created and converted to SP.". Following on that I would do numbers differently than you
The way they come up with the numbers is very counter intuitive (and also not the way i would do them)
So you make $50 SBD and $50 steem power for a blog, for a total of $100
they take $1000 and put it in the vesting fund.
$50 of that is to pay for your new steem power. The other $950 of that is the 19/1 DTO backing that theyre talking about (950:50 = 19:1)
see numbers 'R' fun!