Show me the monthly rentals for all student addresses.
select address_id, monthly_rental from student_addresses
Give me the id of student with the lowest of them.
select student_id from student_addresses order by monthly_rental asc limit 1
What about that student's cell phone number?
select t2.cell_mobile_number from student_addresses as t1 join students as t2 on t1.student_id = t2.student_id order by t1.monthly_rental asc limit 1