These are the questions that come after the warm-up: they need two steps, a join to the same table, or a group result compared with each row. You have emp (employees: id, name, department, hire date, salary, manager id, city), df (Juniper Lane orders) and products.
In an interview, say which edge case you're handling and why: department heads have no manager, two people can share a salary, and some products never sold.