Well, I would set up an equation to figure out how many people voted him favorably:

, where is the number of votes cast in favor.

That would mean after the second go around:

, where in this case is the votes cast on Friday in favor of Alex, 6000 are the votes already cast in favor of Alex, and 12000 are the votes in total that have been cast since voting began.

Solving for :

, will give us an 960 favorable votes cast on Friday.

Can you then use the above to calculate the percentage of favored votes for that day?