How Much Your ROI Has To Be To Return Your Invested SBD When Buying Upvotes(Based On The Price Of SBD)?

I just wanted to make quick post about what your ROI has to be return your invested SBD, so you can make money by reinvesting the same amount over and over again(if you manage to get that ROI).

So you are being payed in SBD and STEEM POWER;
-let A be your total SBD payout(you, as a author will recieve 0.75xA)
-let B be your total SP payout(you, as a author will recieve 0.75xB)
-let k be your multiplier that represent what upvote value will you get based on your invested SBD(e.g if you invest 1 SBD and k=1.5, you will get a 1.5 SBD upvote)

Now, the way you are being payed is like this:
-your post rewards are in units, that we'll call STU's(that "$" sign beyond your post, that represents rewards; you can check http://steem.supply/rewards), let U be your total post rewards;
-when you divide that post rewards by 2, half is given in SBD at exact amount shown by division, so A=0.5xU[SBD]=0.5xUxc[USD],where c is the price of SBD in USD;
-and half is given in SP at the current feed price in USD, so B=0.5xU[USD]=(0.5xU)/d[SP] where d is the price of STEEM in USD;
-so essentially, 1 STU=0.5x(1+c)[USD],where c is the price of SBD in USD(when 1SBD was equal to 1USD, 1 STU was also equal to 1 USD);

Now, you can see that A/B=c, so we have:
-Bxc+B=100% of U => B=100/(1+c)% of U and A=(100-B)% of U
-now, let S be your invested amount of SBD, and B1 and A1 be corresponding percentages to A and B
-since we get 75% of U(if upvote is made 30 min after post was posted...), and want A to be greater or equal to S we have:
-kx0.75xA1xS>=S => k>=1/(0.75*A1)

-Current price of SBD is 2.31$, so A1~0.6978(69.78%) and k>=1/(0.750.6978)=1.91 and that is multiplier you need to return your invested SBD, and beside that get STEEM POWER.
-To calculate ROI for the same reason, we will calculate k1 as k1=0.75k=1.4329 so needed ROI is >=43.29%

In the next post, when I get time to write it, I will also address issue that many bots are lying about their ROI, e.g. they say they will get you 2x your payout, and you send 1 SBD and they give you 2STU upvote which is obviously lower than 2SBD :)