services could be things like "haircut" or "manicure". clients(cid, name, phone) staff(sid, name) appointments(cid, date, time, service, sid) appointments[cid] ⊆ clients[cid] appointments[sid] ⊆ staff[sid] homework questions: a. (15 pts) write the relational algebra for the following query: a. find the appointment time and client name of all appointments for the staff member named jessica on february 9th (assume that you can compare a date value to "february 9" using "