2.  Which branches are using more than 50% of all available services.  Show the branch name and client name. (You cannot assume that you know there are only 6 services).
SELECT cname, bdesc FROM clients, branches, branches_services, services WHERE services.sid = branches_services.sid AND clients.cid = branches.cid AND branches.bid = branches_services.bid AND clients.cid in (SELECT cid FROM branches WHERE (SELECT count(bid) FROM branches_services) > (SELECT count(sid) FROM services)/2);