This set mixes everything from the unit on tables you haven't used yet: employees (Kestrel's staff), suppliers (the companies Kestrel buys from) and tickets (customer support requests).
Before you write each query, preview the table on the left to see its columns and what the values look like. Text matches exactly, so check capital letters in the data. Dates in tickets include a time of day.
There's no new skill here. If you get stuck, the hint names the clause you need; the lesson it comes from has a worked example.