Can you help me with ratios?

Mary had at least an 80% on her test write an inequality to represent this situation

At the newest animated movie, for every 9 children, there are 4 adults. there are a total of 39 children and adults at the movie.

Identify the type of observational study described. a statistical analyst obtains data about ankle injuries by examining a hospital's records from the past 3 years. cross-sectional retrospective prospective