What are the first names and support rep ids for employees serving 10 or more customers?
SELECT T1.FirstName ,  T1.SupportRepId FROM CUSTOMER AS T1 JOIN EMPLOYEE AS T2 ON T1.SupportRepId  =  T2.EmployeeId GROUP BY T1.SupportRepId HAVING COUNT(*)  >=  10
10 veya daha fazla müşteriye hizmet veren çalışanlar için ilk isimler ve destek temsilcileri nelerdir?