Let me give an example. If there are 2 bidders, John & Mike. Let's say John places a bid with $1 steems, and Mike places a bid with $3 steems. The total bid amount will be $4 steems ($1+$3). Since each bidder will get a percentage of total vote value, so John will get 25% ($1 / $4), Mike will get 75% ($3 / $4). Assuming bot's total vote value is $10 steems, then John will get $2.5 (25% * $10) for his post, whereas Mike will get $7.5 (75% * $10). Hope it helps.