classroom$($building$,$ room$\_$number, capacity$)$

department$($dept$\_$name, building, budget$)$

course$($course$\_$id$,$ title, dept$\_$name, credits$)$

instructor$($ID$,$ name, dept$\_$name, salary$)$

section$($course$\_$id$,$ sec$\_$id$,$ semester, year, building, room$\_$number, time$\_$slot$\_$id$)$

teaches$($ID$,$ course$\_$id$,$ sec$\_$id$,$ semester, year$)$

student$($ID$,$ name, dept$\_$name, tot$\_$cred$)$

takes$($ID$,$ course$\_$id$,$ sec$\_$id$,$ semester, year, grade$)$

advisor$($s$\_$ID$,$ i$\_$ID$)$

time$\_$slot$($time$\_$slot$\_$id$,$ day, start$\_$time, end$\_$time$)$

prereq$($course$\_$id$,$ prereq$\_$id$)$

Write the following queries in relational algebra using the above university schema.

a$)$ Find the ID and name of each instructor in the Physics department.

b$)$ Find the ID and name of each instructor in a department located in the building "Watson".

c$)$ Find the ID and name of each student who has taken at least one course in the "Comp. Sci." department.

d$)$ Find the ID and name of each student who has taken at least one course section in the year $2018.$

e$)$ Find the ID and name of each student who hasnot taken any course section in the year $2018.$

Please explain the steps in creating the express!!!! Thank you!!!!