39.选修数学课程的人数从最高峰时期的180人一路下跌至20人，而选修英语的人数则从开始时的24人增长到最后的280人。
The number of people who took math declined all the way from its peak of 180 people to 20 people while the number of people who took English climbed, however, from 24 people at the beginning to 280 people in the end.
40.差不多的状况发生在社会科学与商务这两门课程上，两者分别出现了70%的下降和85%的增长。
A similar situation occurred to social science and business which saw a decrease by 70% and an increase by 85% respectively.
