The population of a town increases by 20% in the first year, decreases by 10% in the second year, and again increases by 20% in the third year. Find the net percentage change in the population over the three years.

In a town with 30,000 professionals, teachers make up 11% of the total professionals. If 46% of teachers are male, what is the number of female teachers in the town?

In a town's professional breakdown, doctors represent 18% and clerks represent 8% of the total professionals. If the number of doctors is 3000 greater than the number of clerks, what is the total number of professionals in the town?