Since 42% of the voters voted and 12000 people voted, we can conclude that:
12,000=42% of the population.
I set this up like this:
12,000=0.42 x, substituting x for the total population.
Divide both sides by 0.42 to get x by itself.
x= 28571.43.
Your final answer is 28,572 people, because you can't have 0.43 of a person.