These are simple UNIX/C programming questions. please complete all of them. Thank you!

QUESTION 12 the number will be printed after the following codes are executed a'=--b + 10 % a- intf("%d %d", a, b); QUESTION 13 Before you leave the RTC 207 lab, you should always logout leave the workstation unattended put a name tag on the workstation to mark its owner lock the screen QUESTION 14 The expression sum sum 10 can be written as_. sum =+ 10 sum +10 sumsum ++ 10 sum ++ 10 QUESTION 15 The login user name of the UNIX system at Norfolk State University is Your last name The first 4 letter of your last name and the last 4 digits of your student ID The first 4 letter of your first name and the last 4 digits of your student ID The lower case s following by the 7-digits of your student ID