Depends. What payout did you pick? If you selected the 50/50 option (which you should at the moment), then the split is like this:

Out of your 100% of rewards ($7), 25% goes to curators (voters). This leaves you with 75% of the total ($5.25).

The 50/50 split means you get half of that as SP (locked down STEEM) and half as SBD (Steem dollars). You get:

• 0.5*$5.25 as SBD = 2.625 SBD
• 0.5*$5.25 worth of SP = $2.625 worth of SP = 0.4 SP at current market rates.

The total value of this will be 0.4 SP *USD$6.58 + 2.625 SBD * USD$8.56 = USD$25.10

If you picked the 100% power up option for your post, then you get 75% of the post value paid in SBD. In that case, you get 0.75 * 7 = $5.25 worth of SP = 0.8 SP = USD$5.25

As you can gather, SBD is currently stupidly overvalued.