sherman, when you have a $1,000 freeplay balance, that's basically the book saying "ok, here's a $1,000 of our money to play with....you can't keep this $1,000....but you CAN use each dollar of it 1x to try to make money off of it. the winnings you CAN keep."
your first play you risked $110 on PHI to win $100....
you won...so you were given $100 balance (the money that you can keep)
but now your Bonus Play is down to only $890 because you risked $110 of that starting $1,000 Bonus Play balance
if you had risked $100 to win $90.9 on that 11/10 bet...
then you're balance would have shown $90.9 and your Bonus Play balance would show $900.
you didn't get shorted $10, you risked $110 to win that $100 and you can only use each dollar of your Bonus Play balance one time.
hope this helps.