Please help with Question A. don't do copy-paste paste. I need help. please

Allegheny Bank has a branch at the local community college. The branch is the busiest at the beginning of the college year when freshman open accounts. This year, freshman arrived at the office at a rate of 4 every 20 minutes. On average, it takes the Allegheny Bank staff person about four minutes to process each account application. The bank is considering having one or two tellers. Each teller is paid $20 per hour and the cost of waiting in line is assumed to be $30 per hour. Based on a single server answer the following: a. What is the probability that less than 2 customers are in the line? b. What is the average time that a student waits before having a teller take care of their request? minutes