200 students=100%
1)We calculate the number of empty seats over the last quarter.
Empty seats=200 - 184=16
2) We calculate the percent of decrease form last quarter, by the rule of three.
200 students------------------100%
16 students--------------------- x
x=(16 students * 100%) / 200 students=8%
Answer: The percent of decrease form las quarter to this quarter has been: 8%