Yx6 for y = 2/3 pls answer this

The american academy of pediatrics wants to conduct a survey of recently graduated family practitioners to assess why they did not choose pediatrics for their specialization. provide a definition of the population, suggest a sampling frame, and indicate the appropriate sampling unit.

Prove that 16^4-2^13-4^5 is divisible by 11.

Hi i’m not sure how to do question 20 if u could explain how to do it that’d b great