Zane had 7/8 of a bottle of water left. Anna had 4/8 of a bottle of water left. How much more water did Zane have than Anna?

Can someone me and plz do the problem

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.

This is about circle theorems. someone asap : (