The Bylaws state that a quorum is 25% of active members (130 x .25 = 33). A specific vote requires 75% of the quorum in order to pass (33 x .75 = 25). My question is, if 100 people are in attendance, and the quorum threshold is only 33, does the 75% of the quorum (25) vote requirement cause the vote to be affirmed even though 75 people might vote against the item?
It depends on what manual of parlimentary procedure is used by the group if any (see comment). But in general i would take the 25 vote requirement to be a floor, but that a majority of those voting, however many they are, must vote in favor for a measure to pass. If that majority is less than 25 votes, it still doesn't pass due to this 75% of a quorum requirement.
Presumably, the 75% of the quorum requirement is an additional requirement for the particular motion over and above the requirement that all motions must be carried by a simple majority of members present and able to vote. So it needs to pass both thresholds.
For your example, 33-50 members present, the threshold is 25 - the 75% of the quorum requirement. For 51+ members present the threshold is 50% of the members present rounded up - the simple majority requirement.
This is an unusual provision and it is likely that the drafters meant 75% of members present and eligible to vote which is much more typical. However, it is unambiguous and workable as written.