What is the course id for the International Finance course?
select course_id from course where title = 'International Finance'
What is the course id for the prerequisite of that course?
select course_id from course where course_id in ( select t1.prereq_id from prereq as t1 join course as t2 on t1.course_id = t2.course_id where t2.title = 'International Finance' )
What is the title of that course?
select title from course where course_id in ( select t1.prereq_id from prereq as t1 join course as t2 on t1.course_id = t2.course_id where t2.title = 'International Finance' )