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i have a question. yesterday my reputation was 31 and today i see 29 why is that?

there is one option upvote only. how can we downvote anyone?

With the flag on the top right of every post and comment.
Downvotes, depending on how much Steem Power the downvoter has, reduce your payout and your reputation score (the latter only if the downvoter has a higher reputation score than you).

i got it.... thank you so much.