Answer:
28
Step-by-step explanation:
Given: In order to vote on any decision, a club requires the presence of  of all club members. to be approved, a proposal needs
 of all club members. to be approved, a proposal needs  of the votes cast. a club has membership of
 of the votes cast. a club has membership of  .
.
To Find: minimum number of votes needed for a proposal to be approved.
Solution: 
Total number of members in club 
Minimum  presence required for vote on any decision 
Minimum presence required for vote 
                                                               
Minimum vote required to approve a proposal 
Total vote cast 
putting value,
Minimum vote required to approve a proposal  
                  
                                                                               
Hence minimum 28 votes are required for a proposal to be approved.