During the first year, the population of a village increased by 5%, and during the next year, it decreased by 5%. If at the end of the second year, the population is 7,980, what was the population at the beginning of the first year?

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?